CHAPTER 9 REVIEW
FORM A
For each of the following problems, please provide the requested information.
(a) State the null and alternate hypotheses and the level of significance. Is the test left-tailed, right-tailed, or
two-tailed?
(b) Identify the appropriate sampling distribution: the standard normal Z or the Student’s t. What is the value
of the sample test statistic?
(c) Find (or estimate) the P-value. Sketch the sampling distribution and show the area corresponding to the Pvalue by your shading.
(d) Based on your answers for parts (a) through (d), will you reject or fail to reject the null hypothesis?
Interpret your conclusion in the context of the application.
1. A large furniture store has begun a new ad campaign on local television. Before the campaign, the long term
mean daily sales were $24,819. A random sample of 40 days during the new ad campaign gave a sample mean
daily sale of x = $25,910. Does this indicate that the population mean daily sales is now more than $24,819?
Use a 1% level of significance. Assume  = $1917.
1. (a) __________________________
____________________________
(b) __________________________
____________________________
(c)
____________________________
(d) __________________________
____________________________
____________________________
2. A new bus route has been established between downtown Denver and Englewood, a suburb of Denver. Dan
has taken the bus to work for many years. For the old bus route, he knows from long experience that the mean
waiting time between buses at his stop was  = 18.3 minutes. However, a random sample of 5 waiting times
between buses using the new route had mean x = 15.1 minutes with sample standard deviation s = 6.2
minutes. Does this indicate that the population mean waiting time for the new route is less than what it used to
be? Use  = 0.05. Assume x is normally distributed.
2. (a) __________________________
____________________________
(b) __________________________
____________________________
(c)
____________________________
(d) __________________________
____________________________
____________________________
3. The State Fish and Game Division claims that 75% of the fish in Homestead Creek are rainbow trout.
However, the local fishing club caught and released 189 fish one weekend. They found that 125 were rainbow
trout. Does this indicate that the percentage of rainbow trout in Homestead Creek is less than 75%? Use  =
0.01.
3. (a) __________________________
____________________________
(b) __________________________
____________________________
(c)
____________________________
(d) __________________________
____________________________
____________________________
4. How tall are college hockey players? The average height has been 71 inches. A random sample of
14 hockey players had a mean height of 72.5 inches. We may assume that x has a normal distribution with  =
0.9 inches. Does this indicate that the population mean height is different from 71 inches? Use 5% level of
significance.
4. (a) __________________________
____________________________
(b) __________________________
____________________________
(c)
____________________________
(d) __________________________
____________________________
____________________________
5. How long does it take to have food delivered? A Chinese restaurant advertises that delivery will be no more
than 30 minutes. A random sample of delivery times is shown below. Based on this sample, is the delivery
time greater than 30 minutes? Use a 5% level of significance. Assume that the distribution of delivery times is
normal.
5.(a) __________________________
____________________________
(b) __________________________
____________________________
x  3.6
s  5.9
(c)
____________________________
(d) __________________________
____________________________
6. A music teacher knows from past records that 60% of students taking summer lessons play the piano. The
instructor believes this proportion may have dropped due to the popularity of wind and brass instruments. A
random sample of 80 students had 43 piano players. Test the instructor’s claim at  = 0.05.
6. (a) __________________________
____________________________
(b) __________________________
____________________________
(c)
____________________________
(d) __________________________
____________________________
____________________________