Question

A doctor at a local hospital is interested in estimating the birth weight of infants. How large a sample must she select if she desires to be 98% confident that the true mean is within 2 ounces of the sample mean? The standard deviation of the birth weights is known to be 5 ounces.
A) 34
B) 5
C) 33
D) 6

Answer 1

You want mean ± 2.33 SEm for 98% confidence interval.

SEm = SD/√n

I'll leave the rest to you.

Answer 2

3.2