STAAR (State of Texas Assessments of Academic Readiness) Algebra I, May 2018, cont.

The State of Texas Assessments of Academic Readiness (STAAR) exam, administered MAY 2018.

More STAAR problems.

Administered May 2018

Read each question carefully. For a multiple-choice question, determine the best answer to the question from the four answer choices provided. For a griddable question, determine the best answer to the question.





11. Which expression is equivalent to x² − 17x − 60?

A (x - 20)(x + 3)
B (x - 5)(x - 12)
C (x - 20)(x - 3)
D (x + 5)(x - 12)

Answer: A (x - 20)(x + 3)
The minus sign in front of the 60 tells you that one factor is positive and one factor is negative. That eliminates Choices B and C.

What are two factors of -60 that add up to -17? -20 + 3 = -17, Choice A is the answer.



12. A zookeeper recorded the feeding schedule for a baby rhinoceros for 20 weeks. The table and scatterplot show the percentage of the baby rhinoceros’s body mass that was used to determine the amount of food given at each feeding as a linear function of its age in weeks.

What is the best prediction of the percentage of the baby rhinoceros’s body mass that should be used to determine the amount of food given at each feeding when it is 25 weeks old?

F 8.5%
G 6%
H 2.5%
J 10%

Answer: G 6%
Put the data into your graphing calculator and do a linear regression. You will get a = -.5448... and b = 19.80...
That makes your line of best fit, rounded to the nearest hundredth, y = -.54x + 19.80.
Substitute 25 for x and you get y = -.54(25) + 19.80 = 6.3, which is approximately 6%, which is Choice G.

13. What are the domain and range of f(x) = −37?

A Domain: All real numbers greater than or equal to −37; Range: All real numbers
B Domain: {−37} ; Range: All real numbers
C Domain: All real numbers ; Range: All real numbers greater than or equal to −37
D Domain: All real numbers ; Range: {−37}

Answer: D Domain: All real numbers ; Range: {−37}
The range is {-37}. No matter what the input is, the output is -37. That is the entirety of the range. That gives you exactly one option, Choice D.

The input is All real numbers. It doesn't matter what x is, and there are no restrictions on it. There are no values that are undefined.



14. The graph of quadratic function p is shown on the grid.

If k(x) = x² and p(x) = k(x) + n, what is the value of n? Record your answer and fill in the bubbles on your answer document.

Answer:
The graph of the parent function k(x) = x² goes through the origin, (0, 0). The illustrated graph of p(x) has its vertex at (0, -6). Therefore, p(x) = x² - 6, which means that n = -6.

You can check this by substituting x = -3 or x = 3. Both numbers squared give 9 which after subtracting 6 becomes 3.



15. Two customers went to a post office to buy postcards and large envelopes. Each postcard costs the same amount, and each large envelope costs the same amount.

• • The first customer paid $12 for 14 postcards and 5 large envelopes.
• • The second customer paid $24.80 for 10 postcards and 15 large envelopes.

What was the cost in dollars of each large envelope?

A $1.42
B $0.35
C $1.15
D $0.63

Answer: A $1.42
The system of equations is as follows:

14x + 5y = 12
10x + 15y = 24.80
multiply the first equation by 3, and then subtract
42x + 15y = 36.00
10x + 15y = 24.80
32x = 11.20
x = 0.35, which is the cost of a postcard
14(.35) + 5y = 12
4.90 + 5y = 12
5y = 7.10
y = 1.42, which is the cost of a large envelope

More to come. Comments and questions welcome.

More STAAR problems.