10.11

oAccording to the California Educational Code (http://www.cde.ca.gov/ls/fa/sf/pegui-demidhi.asp), students in grades 7 through 12 should receive 400 minutes of physical education every 10 school days. A random sample of 48 students has a mean of 385 minutes and a standard deviation of 53 minutes. Test the hypothesis at the .05 level of significance that the sampled population satisfies the requirement.

10.12

oAccording to a 2009 survey based on the United States census (http://www.census.gov/prod/2011pubs/acs-15.pdf), the daily one-way commute time of U.S. workers averages 25 minutes with, we'll assume, a standard deviation of 13 minutes. An investigator wishes to determine whether the national average describes the mean commute time for all workers in the Chicago area. Commute times are obtained fora random sample of 169 workers from this area, and the mean time is found to be 22.5 minutes. Test the null hypothesis at the .05 level of significance.

Chapter 11

11.11

oGive two reasons why the research hypothesis is not tested directly.

11.19

oHow should a projected hypothesis test be modified if you're particularly concerned about

o(a) the type I error?

o(b) the type II error?

11.20

oConsult the power curves in Figure 11.7 to estimate the approximate detection rate, rounded to the nearest tenth, for each of the following situations:

o(a) a four-point effect, with a sample size of 13

o(b) a ten-point effect, with a sample size of 29

o(c) a seven-point effect with a sample size of 18 (Interpolate)

Chapter 12

12.7

oIn Question 10.5 on page 191, it was concluded that, the mean salary among the population of female members of the American Psychological Association is less than that ($82,500) for all comparable members who have a doctorate and teach fulltime.

o(a) Given a population standard deviation of $6,000 and a sample mean salary of$80,100 for a random sample of 100 female members, construct a 99 percent confidence interval for the mean salary for all female members.

80,100 2.58 (6,000 / ) =

o(b) Given this confidence interval, is there any consistent evidence that the mean salary for all female members falls below $82,500, the mean salary for all members?

We can claim, with 99 percent confidence, that the interval between $78,552 and$81,648 includes the true population mean salary for all female members of the American Psychological Association. All of these values suggest that, on average, females' salaries are less than males' salaries.

12.8

oIn Review Question 11.12 on page 218, instead of testing a hypothesis, you might prefer to construct a confidence interval for the mean weight of all 2-pound boxes of candy during a recent production shift.

o(a) Given a population standard deviation of .30 ounce and a sample mean weight of 33.09 ounces for a random sample of 36 candy boxes, construct a 95 percent confidence interval.

o(b) Interpret this interval, given the manufacturer's desire to produce boxes of candy that, on the average, exceed 32 ounces.