Answer:
30 men
Step-by-step explanation:
In order to be sure that the sample mean does differ from the population mean by more than 0.90, the sample size (n) that should be used is given by:
Where 'Z' , for a 95% probability is 1.960, 's' is the standard deviation of 2.5 inches:
Rounding up to the nearest whole number, the sample size should be at least 30 men.