Part a)
The mean height is 69 inches with a standard deviation of 2.5 inches.
If we consider a interval of heights that relies on no more than two standard deviations from the mean, we will cover, approximatelly, 95% of men's heights. Then, we interval that we're looking for is:
Answer: 64 TO 74 INCHES
Part b)
Since [69,74] is half of the interval in the previous answer, we might expect half of 95% as the percentage of men who are in this interval. That is:
Answer: 47.5 PERCENT
Part c)
A interval of heights that relies on no more than one standard deviation from the mean covers, approximatelly, 68% of men's heights. Then, we can consider that the percentage of men that are between 64 and 66.5 inches is given by 47.5 - 68/2 = 13.5.
Answr: 13.5 PERCENT