1. A researcher wished to compare the average amount of time spent in extracurricular activities by high school students in a suburban school district with that in a school district of a large city. The researcher obtained an SRS of 60 high school students in a large suburban school district and found the mean time spent in extracurricular activities per week to be = 6 hours with a standard deviation s1 = 3 hours. The researcher also obtained an independent SRS of 40 high school students in a large city school district and found the mean time spent in extracurricular activities per week to be = 4 hours with a standard deviation s2 = 2 hours. Let µ1 and µ2 represent the mean amount of time spent in extracurricular activities per week by the populations of all high school students in the suburban and city school districts, respectively. If the researcher used the more accurate software approximation to the degrees of freedom, he would have used which of the following for the number of degrees of freedom for the two-sample t procedures?
A. 39
B. 59
C. 98
2. It has been claimed that women live longer than men; however, men tend to be older than their wives. Ages of sixteen husbands and wives from England were obtained. These data should be analyzed with a
A. two-sample t test.
B. paired samples t test.
C. two-sample z test.
3. The heights (in inches) of adult males in the U.S. are believed to be Normally distributed with mean µ. The average height of a random sample of 25 American adult males is found to be = 69.72 inches and the standard deviation of the 25 heights is found to be s = 4.15. A 90% confidence interval for µ is
A. 69.72 ± 1.09.
B. 69.72 ± 1.37.
C. 69.72 ± 1.42.