A standard IQ test has a mean of 98 and a standard deviation of 16. We want to be 99% certain that we are within 8 IQ points of the true mean. Determine the sample size

Answer 1

=NORMINV(0.01/2,0,1)
-2.575829304

=(2.58*16/8)^2
26.6256

round to 26.