More Algebra 2 problems.

__June 2017, Part III__

All Questions in Part III are worth up to 4 credits. Partial credit is possible.

*35. Graph y = log _{2}(x + 3) - 5 on the set of axes below. Use an appropriate scale to include
both intercepts.
*

*Describe the behavior of the given function as x approaches -3 and as x approaches positive infinity.
*

**Answer: **

If you graph y = log_{2}(x + 3) - 5, you will see that it is not defined for x __%lt__ 3.

The y-intercept is at y = log_{2}(0 + 3) - 5 = -3.42.

Solving 0 = log_{2}(x + 3) - 5 gives you the x-intercept at 29.

You can use the calculator, or work it out:

_{2}(x + 3) - 5

5 = log

_{2}(x + 3)

x + 3 = 2

^{5}

x + 3 = 32

x = 29

The best scale to use for the x-axis is 3. Use a scale of 1 for the y-axis.

Check the image below. The table of values is provided for you. It wasn't necessary for the exam, but it would be a good idea to label the intercepts.

Second part: As x approaches -3, the function goes to negative infinity. As x approaches infinity, the function approaches infinity.

*36. Charlie’s Automotive Dealership is considering implementing a new check-in procedure for
customers who are bringing their vehicles for routine maintenance. The dealership will launch
the procedure if 50% or more of the customers give the new procedure a favorable rating when
compared to the current procedure. The dealership devises a simulation based on the minimal
requirement that 50% of the customers prefer the new procedure. Each dot on the graph below
represents the proportion of the customers who preferred the new check-in procedure, each of
sample size 40, simulated 100 times.
*

Assume the set of data is approximately normal and the dealership wants to be 95% confident of its results. Determine an interval containing the plausible sample values for which the dealership will launch the new procedure. Round your answer to the nearest hundredth.

Assume the set of data is approximately normal and the dealership wants to be 95% confident of its results. Determine an interval containing the plausible sample values for which the dealership will launch the new procedure. Round your answer to the nearest hundredth.

*Forty customers are selected randomly to undergo the new check-in procedure and the
proportion of customers who prefer the new procedure is 32.5%. The dealership decides not to
implement the new check-in procedure based on the results of the study. Use statistical evidence
to explain this decision.
*

**Answer: **

The mean is given as 0.506, and one standard deviation is 0.078. To be 95% confident in the result requires two standard deviations, or 2 * 0.078 above or below the mean. So the interval would be:

__<__0.506

__<__0.506 + 2 * 0.078

0.506 - 0.156

__<__0.506

__<__0.506 + 2 * 0.156

0.354

__<__0.506

__<__0.656

0.35

__<__0.506

__<__0.66

In the second part, since 32.5% is below 35.4%, the amount is outside of the 95% confidence interval.

Comments and questions welcome.

More Algebra 2 problems.

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