Question

A nurse at a bcal hosptal is inierested in estimating the bith weight of inlants. How lange a sample must she select if she desires to be 90% confddent that the true mean is within 3 ounces of the sample mean? The population standard deviation of the birth weights is knoen to be 5 ounces.

Answer 1

To estimate the birth weight of infants with a desired margin of error, the nurse needs to select a sample size of approximately 14 infants.

Step-by-step explanation:

To determine how large of a sample the nurse at the hospital needs to select, we can use the formula for the sample size needed for estimating population mean with a known standard deviation. The formula is:

n = (Z * sigma / E) ^ 2

Where:

• n is the required sample size
• Z is the Z-value corresponding to the desired level of confidence (for 90% confidence, Z is approximately 1.645)
• sigma is the population standard deviation
• E is the desired margin of error (in this case, 3 ounces)

Substituting in the values, we get:

n = (1.645 * 5 / 3) ^ 2

Solving the equation, we find that the nurse needs to select a sample size of approximately 14 infants.