9.2 Assignment
AP Statistics
“The nature of work is changing at whirlwind speed. Perhaps now more than ever before, job stress
poses a threat to the health of workers and, in turn, to the health of organizations.” So says the
National Institute for Occupational Safety and Health. Employers are concerned about the effect of
stress on their employees. Stress can lower morale and efficiency and increase medical costs. A large
survey of restaurant employees found that 75% reported that work stress had a negative impact on their
personal life. The human resources manager of a chain of restaurants is concerned that work stress
may be affecting the chain’s employees. She asks a random sample of 100 employees to respond yes
or no to the question, “Does work stress have a negative impact on your personal life?” Of these, 68
say “yes.”
Is there evidence to conclude that the proportion for this chain of restaurants differs from the value
given for the national survey? Use an appropriate inference procedure to support your answer.
LeRoy, a starting player for a major college basketball team, made only 40% of his free throws last
season. During the summer, he worked on developing a softer shot in hopes of improving his free
throw accuracy. In the first eight games of this season, LeRoy made 25 free throws in 40 attempts.
You want to investigate whether LeRoy’s work over the summer will result in a higher proportion of
free throw successes this season.
Identify the population and parameter of interest. Then state null and alternative hypotheses.
State and verify the conditions for performing a significance test.
Calculate the test statistic and the P-value.
What conclusion would you draw at the α = 0.01 level about LeRoy’s free throw shooting?