Question 1
Suppose you want to estimate the difference between two population means correct to within 2.5 with probability 0.95. If prior information suggests that the population variances are both equal to the value 20, and you want to select independent random samples of equal size from the populations, how large should the sample sizes be?
◦ n
1 = n
2 = 44
◦ n
1 = n
2 = 18
◦ n
1 = n
2 = 25
◦ n
1 = n
2 = 62
Question 2
An experiment has been conducted at a university to compare the mean number of study hours expended per week by student athletes with the mean number of hours expended by non athletes. A random sample of 55 athletes produced a mean equal to 20.6 hours studied per week and a standard deviation equal to 5.3 hours. A second random sample of 200 non athletes produced a mean equal to 23.5 hours per week and a standard deviation equal to 4.3 hours. How many students would need to be sampled in order to estimate the difference in means to within 1.5 hours with probability 95%?
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