A nurse 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 99% confident that the true mean is within 2 ounces of the sample mean? The standard deviation of the birth weights is known to be 7 ounces.

Answer 1

99% = mean ± 2.575 SEm

SEm = SD/√n

Answer 2

36