Question

On this problem, the answer has been worked out, but you must fill in the blanks in the solution.A health care professional wishes to estimate the birth weights of infants. How large a sample must be obtained if she desires to be 95% confident that the true mean is within 2 ounces of the sample mean? Assume the population standard deviation is 8 ounces.

Answer 1

Given the formula for the sample n as;

`n=(\frac{Z_{(\alpha)/(2)}\cdot\sigma}{E})^2`
`\begin{gathered} \text{The z-score at 95\% confidence interval = 1.96} \\ \sigma=8 \\ E=2 \end{gathered}`
`\begin{gathered} n=((1.96*8)/(2))^2 \\ n=61.4656 \end{gathered}`

Since the answer has to be whole number, she needs a sample of at least 61 infants.

First box: 1.96

Second box: 8

Third box: 2

Fourth box: 61