## Wednesday, January 31, 2024

### January 2023 Algebra 2 Regents Part IV

This exam was adminstered in January 2023.

More Regents problems.

### Algebra 2 January 2023

Part IV: A correct answer will receive 6 credits. Partial credit can be earned. One computational mistake will lose 1 point. A conceptual error will generally lose 2 points (unless the rubric states otherwise). It is sometimes possible to get 1 point for a correct answer with no correct work shown.

37. A Objects cool at different rates based on the formula below.

T = (T0 - TR)e2rt + TR T0: initial temperature TR: room temperature r: rate of cooling of the object t: time in minutes that the object cools to a temperature, T

Mark makes T-shirts using a hot press to transfer designs to the shirts. He removes a shirt from a press that heats the shirt to 400°F. The rate of cooling for the shirt is 0.0735 and the room temperature is 75°F. Using this information, write an equation for the temperature of the shirt, T, after t minutes.
Use the equation to find the temperature of the shirt, to the nearest degree, after five minutes.
At the same time, Mark’s friend Jeanine removes a hoodie from a press that heats the hoodie to 450°F. After eight minutes, the hoodie measured 270°F. The room temperature is still 75°F. Determine the rate of cooling of the hoodie, to the nearest ten thousandth.
The T-shirt and hoodie were removed at the same time. Determine when the temperature will be the same, to the nearest minute.

Write the equation substituting all values that we know. You should only have t remaining (and the letter e -- don't replace that with a number).

The equation will be T = (400 - 75)e-.0735t + 75.

For the second part, substitute t = 5 and evaluate in your calculator:
T = (400 - 75)e-.0735(5) + 75 = 300.05058... = 300 degrees

In the next part, you are given T and t but you need to find r:
270 = (450 - 75)e-r(8) + 75
195 = (375)e-8r
195/375 = e-8r

loge 195/375 = -8r
r = (loge 195/375)/(-8)
r = 0.08174... = 0.0817.

For the last piece, we need to find t when the two expressions will be equal:
(375)e-0.0817t + 75 = (325)e-0.0735t + 75
(375)e-0.0817t = (325)e-0.0735t
e-0.0817t = (325/375)e-0.0735t
e-0.0817t / e-0.0735t = 13/15
e-0.0082t = 13/15
ln 13/15 = -0.0082t
t = (ln 13/15) / (-0.0082) = 17.451...

You could also have plugged each equation into your graphing calculator and compared the tables of values of the two equations. The intersection would happen at approximately 17 minutes. This will receive full credit if you explain where you got the answer from and likely allows fewer opportunites for mistakes.

As it is, I worked it out just to be sure that I could work it out. And in the end, I had an incorrect answer from putting the last step into the calculator incorrectly. Thankfully, I double-checked my work and discovered an error. Then I had to figure which of the two was incorrect!

End of Exam

How did you do?

More to come. Comments and questions welcome.

More Regents problems.

### I also write Fiction!

You can now order my newest book Burke's Lore, Briefs: A Heavenly Date / My Damned Best Friend, written by Christopher J. Burke, which contains the aforementioned story and a bonus story.
Order the softcover or ebook at Amazon.

Also, check out In A Flash 2020, by Christopher J. Burke for 20 great flash fiction stories, perfectly sized for your train rides.
Available in softcover or ebook at Amazon.

If you enjoy it, please consider leaving a rating or review on Amazon or on Good Reads.

## Tuesday, January 30, 2024

### School Life #39: Helium and Iron

(Click on the comic if you can't see the full image.)
(C)Copyright 2024, C. Burke. "AnthroNumerics" is a trademark of Christopher J. Burke and (x, why?).

Learning was assessed, just not the learning that was expected.

This was just one of those things that pops up in Geometry class when things are written on the board, and they appear to be something else when looked at out of context. And someone who is less aware (or more asleep) might not have the proper context. (Reference "What's a Parabola?")

A new semester is under way. I hope it's fruitful. In the meantime, I'm catching up on old Regents exams so I can avoid rewriting something that needs to be rewritten even though I don't want to rewrite it. (Edit, sure, but rewrite?)

### I also write Fiction!

You can now order my newest book Burke's Lore, Briefs: A Heavenly Date / My Damned Best Friend, written by Christopher J. Burke, which contains the aforementioned story and a bonus story.
Order the softcover or ebook at Amazon.

Also, check out In A Flash 2020, by Christopher J. Burke for 20 great flash fiction stories, perfectly sized for your train rides.
Available in softcover or ebook at Amazon.

If you enjoy it, please consider leaving a rating or review on Amazon or on Good Reads.

Come back often for more funny math and geeky comics.

### January 2023 Algebra 2 Regents, Part III

This exam was adminstered in January 2023.

More Regents problems.

### Algebra 2 January 2023

Part III: Each correct answer will receive 4 credits. Partial credit can be earned. One computational mistake will lose 1 point. A conceptual error will generally lose 2 points (unless the rubric states otherwise). It is sometimes possible to get 1 point for a correct answer with no correct work shown.

33. Solve the equation √(49 - 10x) + 5 = 2x algebraically.

Subtract 5 from both sides to isolate the radical. Square both sides. Then solve the quadratic equation. Finally, discard extraneous solutions that were added when you squared the equation.

You do this by checking the answers that you got.

√(49 - 10x) + 5 = 2x

√(49 - 10x) = 2x - 5

49 - 10x = 4x2 - 20x + 25

0 = 4x2 - 10x - 24

0 = 2x2 - 5x - 12

0 = (2x + 3)(x - 4)

2x + 3 = 0 or x - 4 = 0

x = -3/2 or x = 4

Check -3/2: √(49 - 10(-3/2)) + 5 ?= 2(-3/2)
√(49 - 10(-3/2) ?= -3 - 5 = -8
The square root cannot be negative, so reject this answer.

Check 42: √(49 - 10(4)) + 5 ?= 2(4)
√(9) + 5 ?= 8
3 + 5 = 8 (check!)
x = 4 is the only solution.

34. Joette is playing a carnival game. To win a prize, one has to correctly guess which of five equally sized regions a spinner will land on, as shown in the diagram below.

She complains that the game is unfair because her favorite number, 2, has only been spun once in ten times she played the game.

State the proportion of 2’s that were spun.

State the theoretical probability of spinning a 2.

The simulation output below shows the results of simulating ten spins of a fair spinner, repeated 100 times.

Does the output indicate that the carnival game was unfair? Explain your answer.

Empirical probability is 1/10 because there was 1 positive result in 10 tries.

Theoretical probability is 1/5 because the number 2 covers one-fifth of the area of the wheel. There are five possible outcome and each should be as likely to occur as the others.

The chart shows that in 21 out of 100 simulations a result of 1/10, or 0.10 occured. This is not an unusual outcome.

If you think about it, with 5 possible outcomes, in 10 spins, a result of 2 should happen two times. If a result of 2 only happened one time, or even 3 times, in 10 spins that wouldn't be an unlikely occurrence because variations can be expected.

35. Graph c(x) = -9(3)x - 4 + 2 on the axes below.
Describe the end behavior of c(x) as x approaches positive infinity.
Describe the end behavior of c(x) as x approaches negative infinity.

You can use your graphing calculator to get the table of values for where to plot the points. Your graph should look like this one below.

The end behavior of c(x): as x approaches positive infinity, c(x) approaches negative infinity. As x approaches negative infinity, c(x) approaches 2.

36. The monthly high temperature (°F) in Buffalo, New York can be modeled by B(m) = 24.9sin(0.5m - 2.05) + 55.25, where m is the number of the month and January = 1.
Find the average rate of change in the monthly high temperature between June and October, to the nearest hundredth.
Explain what this value represents in the given context.

June is the 6th month and October is the 10th month. Find B(6) and B(10). Subtract B(10) - B(6) and divide the difference by (10 - 6), which is 4 to find the average monthly change.

B(6) = 24.9*sin(0.5(6) - 2.05) + 55.25 = 75.5040
B(10) = 24.9*sin(0.5(10) - 2.05) + 55.25 = 59.9915

(B(10) - B(6)) / 4 = (59.9915 - 75.5040) / 4 = -3.878 = -3.88

This means that for each month, the temperature is decreasing by 3.88 degrees.

End of Part III

How did you do?

More to come. Comments and questions welcome.

More Regents problems.

### I also write Fiction!

You can now order my newest book Burke's Lore, Briefs: A Heavenly Date / My Damned Best Friend, written by Christopher J. Burke, which contains the aforementioned story and a bonus story.
Order the softcover or ebook at Amazon.

Also, check out In A Flash 2020, by Christopher J. Burke for 20 great flash fiction stories, perfectly sized for your train rides.
Available in softcover or ebook at Amazon.

If you enjoy it, please consider leaving a rating or review on Amazon or on Good Reads.

## Monday, January 29, 2024

### January 2023 Algebra 2, Part II

This exam was adminstered in January 2023.

More Regents problems.

### Algebra 2 January 2023

Part II: Each correct answer will receive 2 credits. Partial credit can be earned. One mistake (computational or conceptual) will lose 1 point. A second mistake will lose the other point. It is sometimes possible to get 1 point for a correct answer with no correct work shown.

25. Algebraically determine the zeros of the function below.

r(x) = 3x3 + 12x2 - 3x - 12

Set the expression equal to 0. Then factor by grouping.

3x3 + 12x2 - 3x - 12 = 0

3x3 - 3x + 12x2 - 12 = 0

3x(x2 - 1) + 12(x2 - 1) = 0

(3x + 12)(x2 - 1) = 0

(3x + 12)(x - 1)(x + 1) = 0

3x + 12 = 0 or x - 1 = 0 or x + 1 = 0

x = -4 or x = 1 or x = -1

26. Given a > 0, solve the equation ax + 1 = ∛(a2) for x algebraically

Cube both sides of the equation to get rid of the radical and then solve the equation that results from the exponents being equal.

ax + 1 = ∛(a2)
a3x + 3 = a2
3x + 3 = 2
3x = -1
x = -1/3

27. Given P(A) = 1/3 and P(B) = 5/12, where A and B are independent events, determine P(A ∩ B).

The probably of two independent events happening in the probability of one of them happening times the probability of the other.

P(A ∩ B) = (1/3)(5/12) = 5/36.

28. The scores on a collegiate mathematics readiness assessment are approximately normally distributed with a mean of 680 and a standard deviation of 120.

Determine the percentage of scores between 690 and 900, to the nearest percent.

Use your graphing calculator. Find the function normalcdf.

Enter the following command: normalcdf(690,900,680,120) for the range minimum and maximum, followed by the median and the standard deviation. The answer will be 43%.

If you estimate it using a standard deviation chart, you won't get an exact answer.

29. Consider the data in the table below.

 x 1 2 3 4 5 6 y 3.9 6 11 18.1 28 40.3

State an exponential regression equation to model these data, rounding all values to the nearest thousandth.

Put the data into List 1 and List 2 on your graphing calculator. Run a Exponential Regression (ExpReg).

You should get the following output: a = 2.4585... and b = 1.6159...

The equation you want is y = (2.459)(1.616)x

30. Write the expression A(x) • B(x) - 3C(x) as a polynomial in standard form.

A(x) = x3 + 2x - 1
B(x) = x2 + 7
C(x) = x4 - 5x

Multiply the first two expression A(x) and B(x). Subtract the product of 3 times C(x).

(x3 + 2x - 1)(x2 + 7) - 3(x4 - 5x)
x5 + 7x3 + 2x3 + 14x - x2 - 7 - 3x4 + 15x
x5 + 9x3 - x2 + 14x - 7 - 3x4 + 15x
x5 - 3x4 + 9x3 - x2 + 29x - 7

31. Over the set of integers, completely factor x4 - 5x2 + 4

The first step is to factor it the way you would factor y2 - 5y + 4. Then factor the quadratic expression that result.

x4 - 5x2 + 4

(x2 - 4)(x2 - 1)

(x - 2)(x + 2)(x - 1)(x + 1)

32. Natalia’s teacher has given her the following information about angle θ.

• π < θ < 2π • cos θ = &sqrt;(3)/4

Explain how Natalia can determine if the value of tan θ is positive or negative.

Cosine is positive in Quadrants I and IV, and π < θ < 2π indicates Quadrants III and IV, so θ must put the angle into quadrant IV.

Tangent is negative in Quadrant IV.

End of Part II

How did you do?

More to come. Comments and questions welcome.

More Regents problems.

### I also write Fiction!

You can now order my newest book Burke's Lore, Briefs: A Heavenly Date / My Damned Best Friend, written by Christopher J. Burke, which contains the aforementioned story and a bonus story.
Order the softcover or ebook at Amazon.

Also, check out In A Flash 2020, by Christopher J. Burke for 20 great flash fiction stories, perfectly sized for your train rides.
Available in softcover or ebook at Amazon.

If you enjoy it, please consider leaving a rating or review on Amazon or on Good Reads.

## Sunday, January 28, 2024

### August 2023 Geometry Regents Part IV

This exam was adminstered in August 2023.

### August 2023 Geometry, Part IV

A correct answer is worth 6 credits. Partial credit can be given for correct statements in the proof.

35. In the diagram below of quadrilateral FACT, BR intersects diagonal AT at E, AF || CT, and AF ≅ CT.

Prove: (AB)(TE) = (AE)(TR)

This question is a little different, because most proofs of this type usuablly rely on find two traingles to be congruent via SSS, SAS, etc., and then showing two parts to be congruent using CPCTC. This one doesn't do that. This one asks you to prove a multiplication statement is true, but these products are the results of cross-multiplying the numerators and denominators of a proportion. You need to show that the two triangles are similar, not congruent, and then cross multiply the sides because the product of the means will equal the product of the extremes.

Also, notice that you are only told that this is a "quadrilateral", not a parallelogram. This was the case in June, as well. I wonder if it's going to be a recurring theme going forward.

Your proof should look like this:

 Statement Reasons Quadrilateral FACT, BR intersects diagonal AT at E, AF || CT, and AF ≅ CT. Given FACT is a parallelogram A quadrilateral with one pair of sides that are parallel and congruent is a parallelogram ∠ BAE ≅ ∠ RTE Alternate Interior Angles ∠ AEB ≅ ∠ TER Vertical Angles △AEB ~ △RET AA Postulate (AB) / (AE) = (TR) / (TE) Corresponding sides of similar triangles are proportional (AB)(TE) = (AE)(TR) The product of the means = the product of the extremes

Each statement is important. If you leave any out, you will lose one credit. However, if you have a couple of statements correct and the semblance of a proof, you should still earn two points for the question.

Also note that I wrote "The product of the means = the product of the extremes" instead of "cross multiplication", which is in essence the same thing, except that it is an instruction and not a justification or Reason (theorem, postualte, etc.). You could argue this point all you want, but there is an example in the Model Response Set where the only point lost is for the final step where "Cross multiply" is written, and the Regents literally calls out this step as an incorrect reason.

End of Exam

How did you do?

### I also write Fiction!

You can now order my newest book Burke's Lore, Briefs: A Heavenly Date / My Damned Best Friend, written by Christopher J. Burke, which contains the aforementioned story and a bonus story.
Order the softcover or ebook at Amazon.

Also, check out In A Flash 2020, by Christopher J. Burke for 20 great flash fiction stories, perfectly sized for your train rides.
Available in softcover or ebook at Amazon.

If you enjoy it, please consider leaving a rating or review on Amazon or on Good Reads.

## Saturday, January 27, 2024

### August 2023 Geometry Regents Part III

This exam was adminstered in August 2023.

### August 2023 Geometry, Part III

Each correct answer is worth up to 4 credits. Partial credit can be given. Work must be shown or explained.

32. Josh is making a square-based fire pit out of concrete for his backyard, as modeled by the right prism below. He plans to make the outside walls of the fire pit 3.5 feet on each side with a height of 1.5 feet. The concrete walls of the fire pit are going to be 9 inches thick.

If a bag of concrete mix will fill 0.6 ft3, determine and state the minimum number of bags needed to build the fire pit.

First you need to find the Volume, which is length * width * height (rember that it has a sqware base) minus the volume of the hole in the center, which has the same height but is 18 inches less wide and long. Also keep in mind that they are mixing feet and inches in this problem. (Guess what! Real life does that, too!)

Nine inches is .75 feet, and 18 inches is 1.5 feet. Thus, 3.5 - 1.5 = 2.0 feet.

Volume = (3.5)(3.5)(1.5) - (2)(2)(1.5) = 12.375 ft3

If one bag of concrete mix fills 0.6 ft3, then the required number will be 12.375/0.6 = 20.625 or 21 when rounded up. You must round up or you will not have enough concrete mix to complete the job.

33. A telephone pole 11 meters tall needs to be stabilized with a support beam, as modeled below.

Two conditions for proper support are:

• The beam reaches the telephone pole at 70% of the telephone pole’s height above the ground.

• The beam forms a 65° angle with the ground.

Determine and state, to the nearest tenth of a meter, the length of the support beam that meets these conditions for this telephone pole.

Determine and state, to the nearest tenth of a meter, how far the support beam must be placed from the base of the pole to meet the conditions.

First, find 70% of 11 meters (by multiplying) to find how far up the pole the beam will reach. Then use the sin 65° to find the length of the beam, and either tan 65° or the Pythagorean Theorem to find the distance on the ground.

11 * .7 = 7.7 meters.

sin 65° = 7.7 / x
x = 7.7 / sin 65° = 8.46 = 8.5 meters

tan 65° = 7.7 / y
y = 7.7 / tan 65° = 3.59 = 3.6 meters

Look at these answers. The beam is 8.5 meters, which is reasonable for the hypotenuse when the longer leg is 7.7. And the base is 3.6 meters, which is less than half of 7.7, which is reasonable for the side opposite a 25 degree angle. If the numbers you got seem extremely large or extremely small, you may have done one of three things: used radians instead of degrees, entered the ratio incorrectly (or used the wrong one), or forgot a decimal point somewhere.

34. The coordinates of the vertices of quadrilateral ABCD are A(0,4), B(3,8), C(8,3), and D(5,-1).

Prove that ABCD is a parallelogram, but not a rectangle.
[The use of the set of axes below is optional.]

Use the grid if you want to visualize the problem better. You can also use it to help with finding slopes.

A parallelogram has two pairs of parallel sides, and those sides will therefore have the same slope. In a rectangle, the sides must be perpendicular, which means that the slopes are inverse reciprocals and that the products of the slopes of the two lines will be -1.

Find all four slopes. Show that the opposite sides have the same slope. Show that the consecutive sides are not perpendicular. Then write your concluding statement.

Slope of AB = (8-4) / (3-0) = 4/3. Slope of BC = (3-8) / (8-3) = -5/5 = -1.
Slope of CD = (-1-3) / (5-8) = -4/-3 = 4/3. Slope of DA = (4-(-1)) / (0-5) = 5/-5 = -1.

AB || CD and BC || DA because they have the same slopes, therefore ABCD is a parallelogram.

Slope of AB * Slope of BC = (4/3)(-1) = -4/3. The slopes are not inverse reciprocals, so the lines are not perpendicular. Therefore, ABCD is NOT a rectangle.

Anther method:

Paralelograms have a lot of properties, as do rectangles. If you don't mind use the distance formula (Pythagorean Theorem, if you graphed ABCD), you can show that the opposites sides are congruent, which makes it a parallelogram, but the diagonals are NOT congruent, which means is could not be a rectangle.

This is a valid option. However, I'd prefer to use the slope formula over the distance formula is I could. You basically have to find the slope to use the distance formula.

End of Part III

How did you do?

### I also write Fiction!

You can now order my newest book Burke's Lore, Briefs: A Heavenly Date / My Damned Best Friend, written by Christopher J. Burke, which contains the aforementioned story and a bonus story.
Order the softcover or ebook at Amazon.

Also, check out In A Flash 2020, by Christopher J. Burke for 20 great flash fiction stories, perfectly sized for your train rides.
Available in softcover or ebook at Amazon.

If you enjoy it, please consider leaving a rating or review on Amazon or on Good Reads.

## Friday, January 26, 2024

### August 2023 Geometry Regents Part II

This exam was adminstered in August 2023.

### August 2023 Geometry, Part II

Each correct answer is worth up to 2 credits. Partial credit can be given. Work must be shown or explained.

25. On the set of axes below, congruent quadrilaterals ROCK and R'O'C'K' are graphed.

Describe a sequence of transformations that would map quadrilateral ROCK onto quadrilateral R'O'C'K'.

The figure has to move from Quadrant IV to Quadrant II. Inspection shows that the orientation of the quadrilateral has rotated. However, a rotation about the origin will not create the image of K at (-1,1), so a translation must follow.

Rotate ROCK 180 degrees around the origin. Then translate the image 2 to the left and 1 up.

There are many possible answers involding rotations around different centers, or reflections across the x-axis and y-axis or even other lines.

26. In triangle CEM, CE = 3x + 10, ME = 5x - 14, and CM = 2x - 6. Determine and state the value of x that would make △CEM an isosceles triangle with the vertex angle at E.

If the vertex angle is E then sides CE and ME must be congruent and their lengths are equal.

Therefore,

5x - 14 = 3x + 10
2x = 24
x = 12

27. A flagpole casts a shadow on the ground 91 feet long, with a 53° angle of elevation from the end of the shadow to the top of the flagpole.

Determine and state, to the nearest tenth of a foot, the height of the flagpole.

The height and the shadow mean that we need to use tangent. (We aren't concerned with the hypotenuse of the right triangle created.

The height is opposite the 53° angle and the shadow on the ground is adjacent to it.

tan 53 = x / 91
x = 91 tan 53 = 120.76... = 120.8 feet

28. A man is spray-painting the tops of 10 patio tables. Five tables have round tops, with diameters of 4 feet, and five tables have rectangular tops, with dimensions of 4 feet by 6 feet. A can of spray paint covers 25 square feet. How many cans of spray paint must be purchased to paint all of the tabletops?

Find the area of one circle (πr2) and multiply by 5. Find the area of one rectangle (A=LW) and multiply by 5.

A = 5π(2)2 + 5(4)(6) = 182.83

Divide this by 25 and round up to the next can: 182.83 / 25 = 7.3...

8 cans of paint are needed.

If you don't round up, you will not have enough paint to finish the job.

29. Using a compass and straightedge, construct a midsegment of △AHL below. [Leave all construction marks.]

To construct a midsegment, you need two midpoints. To get two midpoints, you need to construct two perpendicular bisectors. You have a choice of which side you want to bisect. You may NOT use a ruler to measure the midpoints.

From point H, make an arc that is more than half the length of HL and swing it across HL and HA. (You could make two separate arcs, but there's no reason not to use the same one.

From point A, make an arc that intersects the first arc in two places. From point L, construct a third arc that intersect the arc drawm from point H.

Draw the two perpendicular bisectors. These will give you the midpoints. Use a straightedge to connect the midpoints. This is the midsegment, which is half the size of AL and parallel to AL.

30. Right triangle STR is shown below, with m∠T = 90°. Altitude TQ is drawn to SQR, and TQ = 8.

If the ratio SQ:QR is 1:4, determine and state the length of SR.

Label SQ x and QR 4x. The product of (SQ)(QR) is equal to the square of (QT) by the Right Triangle Altitude Theorem.

(x)(4x) = 82

4x2 = 64

x2 = 16

x = 4

SR is x + 4x = 5x, and x = 4, so 5x = 5(4) = 20. SR = 20.

31. Line AB is dilated by a scale factor of 2 centered at point A.

Evan thinks that the dilation of AB will result in a line parallel to AB, not passing through points A or B.

Nathan thinks that the dilation of AB will result in the same line, AB.

Who is correct?

Explain why.

Nathan is correct because every point on line AB will move twice as far from A in the same direction along the line AB. Also, since the image of point A will conincide with point A, parallel lines aren't possible.cimal because it's infinite.

End of Part II

How did you do?

### I also write Fiction!

You can now order my newest book Burke's Lore, Briefs: A Heavenly Date / My Damned Best Friend, written by Christopher J. Burke, which contains the aforementioned story and a bonus story.
Order the softcover or ebook at Amazon.

Also, check out In A Flash 2020, by Christopher J. Burke for 20 great flash fiction stories, perfectly sized for your train rides.
Available in softcover or ebook at Amazon.

If you enjoy it, please consider leaving a rating or review on Amazon or on Good Reads.

## Thursday, January 25, 2024

### August 2023 Algebra 1 Regents Part IV

This exam was adminstered in August 2023.

More Regents problems.

### August 2023

Part IV: A correct answer will receive 6 credits. Partial credit can be earned.

37. Lydia wants to take art classes. She compares the cost at two art centers. Center A charges \$25 per hour and a registration fee of \$25. Center B charges \$15 per hour and a registration fee of \$75. Lydia plans to take x hours of classes.

Write an equation that models this situation, where A represents the total cost of Center A.

Write an equation that models this situation, where B represents the total cost of Center B

If Lydia wants to take 10 hours of classes, use your equations to determine which center will cost less.

Graph your equations for Center A and Center B on the set of axes below.

For Center A: y = 25x + 25

For Center B: y = 15x + 75

Substitute x = 10 into each equation:

A: y = 25(10) + 25 = 275
B: y = 15(10) + 75 = 225

Center B will cost less to take 10 hours of classes.

The graph is below:

End of Exam

How did you do?

More to come. Comments and questions welcome.

More Regents problems.

### I also write Fiction!

You can now order my newest book Burke's Lore, Briefs: A Heavenly Date / My Damned Best Friend, written by Christopher J. Burke, which contains the aforementioned story and a bonus story.
Order the softcover or ebook at Amazon.

Also, check out In A Flash 2020, by Christopher J. Burke for 20 great flash fiction stories, perfectly sized for your train rides.
Available in softcover or ebook at Amazon.

If you enjoy it, please consider leaving a rating or review on Amazon or on Good Reads.

## Wednesday, January 24, 2024

### August 2023 Algebra 1 Regents Part III

This exam was adminstered in August 2023.

More Regents problems.

### August 2023

Part III: Each correct answer will receive 4 credits. Partial credit can be earned.

33. The senior class at Hills High School is purchasing sports drinks and bottled water to sell at the school field day. At the local discount store, a case of sports drinks costs \$15.79, and a case of bottled water costs \$5.69. The senior class has \$125 to spend on the drinks.
If x represents the number of cases of sports drinks and y represents the number of cases of bottled water purchased, write an inequality that models this situation.

Nine cases of bottled water are purchased for this year’s field day. Use your inequality to determine algebraically the maximum number of full cases of sports drinks that can be purchased.

They have to spend less than or equal to \$125.

15.79x + 5.69y < 125

For the second part, substitute y = 9 and solve the inequality for x.

15.79x + 5.69(9) < 125
15.79x + 51.21 < 125
15.79x < 73.79
x < 4.67...

The maximum is four full cases of sports drink.

34. The path of a rocket is modeled by the function h(t) = -4.9t2 + 49t, where h is the height, in meters, above the ground and t is the time, in seconds, after the rocket is launched. Sketch the graph on the set of axes below.
Her data are modeled on the graph below.

State the vertex of this function.
Explain what the vertex means in the context of this situation.

Use your graphing calculator to find the table of values for the function. The vertex is the highest point and the time at the vertex will be halfway to the time that it lands.

Plot the following points (0,0), (1,44.1), (2,78.4), (3.102.9), (4,117.6), (5,122.5), (6,117.6), etc.

The "et cetera" is because we found the axis of symmetry at x = 5, so for 6 < x < 11, the values will repeat. "What goes up must come down."

The vertex is (5,122.5) and in this context it is the maximum height that the rocket will reach will be 122.5 meters which it will reach in 5 seconds.

35.A software company kept a record of their annual budget for advertising and their profit for each of the last eight years. These data are shown in the table below.

Write the linear regression equation for this set of data.

State, to the nearest hundredth, the correlation coefficient of these linear data.

State what this correlation coefficient indicates about the linear fit of the data.

Place all the information into a list on your graphing calculator. Then perform a linear regression. DIAGNOSTICS ON needs to be specified on the calculator, or you will not see the correlation coefficient.

You should get the results a = 0.41, b = -2.31, and r = 0.99, when rounded to two decimal places.

The regression would be y = 0.41x - 2.31.

The correlation coefficient is 0.99, which indicates that there is a very strong, positive correlation between the annual advertising budget and profit.

36. Graph the following system of inequalities on the set of axes below:
-2y < 3x + 12
x > -3

Label the solution set S.

Allison thinks that (2,-9) is a solution to this system. Determine if Allison is correct.

Rewrite the flip equation. Flip the inequality sign when dividing by a negative number.

Greater than means it will be a broken line and the shading will be above the line.

x > -3 is a solid, vertical line above and below the x-axis where x is equal to 3. You will shade to the RIGHT of the line, where the x values are greater than -3.

Look at the graph:

Allison is INCORRECT that (2,-9) is a solution to the system. (2,-9) is a point on the broken line, and points on the broken line are not part of the solution.

End of Part III

How did you do?

More to come. Comments and questions welcome.

More Regents problems.

### I also write Fiction!

You can now order my newest book Burke's Lore, Briefs: A Heavenly Date / My Damned Best Friend, written by Christopher J. Burke, which contains the aforementioned story and a bonus story.
Order the softcover or ebook at Amazon.

Also, check out In A Flash 2020, by Christopher J. Burke for 20 great flash fiction stories, perfectly sized for your train rides.
Available in softcover or ebook at Amazon.

If you enjoy it, please consider leaving a rating or review on Amazon or on Good Reads.

## Monday, January 22, 2024

### Giving 100%

(Click on the comic if you can't see the full image.)
(C)Copyright 2024, C. Burke. "AnthroNumerics" is a trademark of Christopher J. Burke and (x, why?).

When you give all you have to give, that's giving 100%. The math checks.

I find it hard to believe that I have not used the A.P. character in close to seven years, not that it's easy to search. I do have an "AP" tag, but I only used it 3 times. (I have since added it to a couple other entries.) And, apparently, I haven't used his name in the comments. (Unless I have a change of heart, it'll be Dexter Locke.)

This was actually going to be posted after a long day of grading yesterday (Sunday). And then my PC froze. I didn't want to reboot and lose stuff, so I waited it out. Usually, it unfreezes in about a half hour from whatever background process it decides to run. This time, it was frozen into the evening after the point where I didn't want to sit at the PC. And it was still hanging this morning. I unplugged it.

Funny thing is that I do have a new PC right next to it, but it doesn't have all the software tht I like and it doesn't have all the files on it yet. I know, I should just migrate everything already. I'm getting to it.

### I also write Fiction!

You can now order my newest book Burke's Lore, Briefs: A Heavenly Date / My Damned Best Friend, written by Christopher J. Burke, which contains the aforementioned story and a bonus story.
Order the softcover or ebook at Amazon.

Also, check out In A Flash 2020, by Christopher J. Burke for 20 great flash fiction stories, perfectly sized for your train rides.
Available in softcover or ebook at Amazon.

If you enjoy it, please consider leaving a rating or review on Amazon or on Good Reads.

Come back often for more funny math and geeky comics.

### August 2023 Algebra 1 Regents Part II

This exam was adminstered in August 2023.

More Regents problems.

### August 2023

Part II: Each correct answer will receive 2 credits. Partial credit can be earned. One mistake (computational or conceptual) will lose 1 point. A second mistake will lose the other point. It is sometimes possible to get 1 point for a correct answer with no correct work shown.

25. Classify the expression (2 / SQRT(144)) + (SQRT(169)) / 3) as rational or irrational. Explain your reasoning.

The expression is rational because the sqaure root of 144 is 12 and the square root of 169 is 13. 2/12 and 13/3 are rational numbers and the sum of two rational numbers is always rational.

26. Julia surveyed 150 of her classmates at City Middle School to determine their favorite animals. Of the 150 students, 46% were male.

Forty-two students said their favorite animal was a horse, and 1/3 of those students were female.

Of the 60 students who said dolphins were their favorite animal, 30% were male.

Using this information, complete the two-way frequency table below.

Fill in the values that you know: 150, 42, 60. Calculate the fractions and decimals: 46% of 150 is 69, 1/3 of 42 is 14, 30% of 60 is 18.

Fill in the rest of the columns and rows based on the information you have been given or have calculated.

27. Bryan said that the piecewise function graphed below has a domain of all real numbers.

A friend tells her that the number of blocks in the pattern is increasing exponentially.
Is her friend correct?

State two reasons why Bryan is incorrect.

Bryan is incorrect because the domain has a maximum at x = 4 and because the value x = 3 is not defined.

28. The formula d = t(vi + vf) / 2 is used to calculate the distance, d, covered by an object in a given period of time, t. Solve the formula for vf, the final velocity, in terms of d, t, and vi, the initial velocity.

You don't need to understand what the formula means or where it is used. All you need to realize s that this is a Literal Equation and the variables can be manipulated. That is, they can be moved from one side to the other.

Use inverse operations. Divide both sides by t. Multiply both sides by 2. Then subtract the initial velocity, which will leave the final velocity by itself.

d = t(vi + vf) / 2

2d = t(vi + vf)

2d / t = vi + vf

(2d / t) - vi = vf

29.Solve x2 - 9x = 36 algebraically for all values of x.

Subtract 36 from both sides of the equation and then factor.

x2 - 9x = 36

x2 - 9x -36 = 0

(x - 12)(x + 3) = 9

x - 12 = 0 or x + 3 = 0

x = 12 or x = -3

30. Determine the common difference of the arithmetic sequence in which a1 = 5 and a5 = 17.

Determine the 21st term of this sequence.

The common difference is similar to the slope between the points (1,5) and (5,17).

d = (17 - 5) / (5 - 1) = 12/4 = 3. The common difference is 3.

The 21st term can be found by multiplying the difference, 3, by 1 less than the term, n - 1, or 20, and then add the initial term, 5.

That is a21 = 5 + 3(21 - 1) = 65.

31. Factor 18x2 - 2 completely.

"Factor completely" almost always means multiple steps. Remove the Common Factor (2) from each term and then factor the binomial using the Difference of Squares Rule.

18x2 - 2 = 2(9x2 - 1) = 2(3x + 1)(3x - 1)

32. Solve x2 + 3x - 9 = 0 algebraically for all values of x. Round your answer to the nearest hundredth.

The polynomial can't be factored in the easy way. The "round your answer" is a hint that you will get irrational numbers for solutions. Use the quadratic formula.

Look at the image below.

Rounded, the solutions are x = 1.85 and x = -4.85.

End of Part II

How did you do?

More to come. Comments and questions welcome.

More Regents problems.

### I also write Fiction!

You can now order my newest book Burke's Lore, Briefs: A Heavenly Date / My Damned Best Friend, written by Christopher J. Burke, which contains the aforementioned story and a bonus story.
Order the softcover or ebook at Amazon.

Also, check out In A Flash 2020, by Christopher J. Burke for 20 great flash fiction stories, perfectly sized for your train rides.
Available in softcover or ebook at Amazon.

If you enjoy it, please consider leaving a rating or review on Amazon or on Good Reads.