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 90% confident that her estimate is within 4 ounces of the true mean

Answer 1

Without the population standard deviation, we cannot calculate the required sample size for the doctor to estimate the birth weight of infants with 90% confidence within 4 ounces of the true mean.

Step-by-step explanation:

To determine the sample size needed for a doctor to estimate the birth weight of infants within 4 ounces of the true mean with 90% confidence, one would typically use a sample size calculation formula for estimating a population mean. This formula requires knowledge of the population standard deviation, the desired margin of error, and the z-score corresponding to the desired confidence level. However, the population standard deviation is not provided in the question, which is necessary information to proceed. When the standard deviation is unknown and the sample size is small, one might use the t-distribution. But since we don't have enough information, we cannot give a specific answer on how large the sample must be.