The heights of 15-year-old American boys, in inches, are normally distributed with mean and standard deviation I select a simple random sample of four 15-year-old American boys and measure their heights. The four heights, in inches, are 63 69 62 66. Based on these data, a 99% confidence interval for , in inches, is a. 65.00 1.55.
b. 65.00 2.35.
c. 65.00 3.09.
d. 65.00 4.07.

15. If I wanted the margin of error for the 99% confidence interval to be 1 inch, I should select a simple random sample of size
a. 2.
b. 7.
c. 16.
d. 39.

16. In formulating hypotheses for a statistical test of significance, the null hypothesis is often
a. a statement of “no effect” or “no difference.”
b. the probability of observing the data you actually obtained.
c. a statement that the data are all 0.
d. 0.05.