Suppose You Want to Estimate the Difference Between Two Population $n _ { 1 } = n _ { 2 } = 18$

Multiple Choice

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?

A) $n _ { 1 } = n _ { 2 } = 18$
B) $n _ { 1 } = n _ { 2 } = 25$
C) $\mathrm { n } _ { 1 } = \mathrm { n } _ { 2 } = 44$
D) $\mathrm { n } _ { 1 } = \mathrm { n } _ { 2 } = 62$