Question

The ages of a group of

149

randomly selected adult females have a standard deviation of

17.5

years. Assume that the ages of female statistics students have less variation than ages of females in the general​ population, so let

sigma

equals17.5years for the sample size calculation. How many female statistics student ages must be obtained in order to estimate the mean age of all female statistics​ students? Assume that we want

95

​%

confidence that the sample mean is within​ one-half year of the population mean. Does it seem reasonable to assume that the ages of female statistics students have less variation than ages of females in the general​ population?

Answer 1

Solution :

Z/2 = Z0.025 = 1.96  

sample size = n = [Z/2* / E] 2

n = [1.96 * 17.5 / 0.5 ]2

n = 4705.96

Sample size = n = 4706

Yes,because statistic students are typically younger than people in the general population.