Question

A private medical clinic wants to estimate the true mean annual income of its patients. The clinic needs to be within $500 of the true mean. The clinic estimates that the true population standard deviation is around $2,300. If the confidence level is 95%, find the required sample size in order to meet the desired accuracy.

Answer 1

Formula:
n = [(z-value * sd)/E]^2
...where n = sample size, z-value will be 1.96 for 95% interval, sd = 2300, E = 500, ^2 means squared, and * means to multiply.

Plug the values into the formula and finish the calculation. Round your answer to the next highest whole number.

Answer 2

82