A researcher wants to estimate the mean age of all Business Week readers at a 99% confidence level. The standard deviation of ages of all Business Week readors is nine years. The sample size that will yield a maximum error of estimate within three years of the population mean is at least:

A. 60
B. 97
C. 185
D. 8

A. 60

Step-by-step explanation:

We have that to find our level, that is the subtraction of 1 by the confidence interval divided by 2. So:

Now, we have to find z in the Ztable as such z has a pvalue of .

So it is z with a pvalue of , so

Now, find the margin of error M as such

In which is the standard deviation of the population and n is the size of the sample.

We have to find:

n when . So

Dividing both sides by 3

We round up, so the correct answer is:

A. 60

is there any photos or whatever?