Question

The mean systolic blood pressure of adult males is normally
distributed with a mean of 138 (millimeters of
mercury) and a standard deviation of 9.7. What percent
of adult males have blood pressure between 161.28 and
164.9?

Answer 1

Find the number of standard deviations from the mean (above) for each of the limits. For example, (161.28-138)/9.7 = 2.4
So look up the normal distribution table and find the fraction (out of 1) that is between the two limits, +2.4 σ and +____ σ.
Change the fraction to percent.

Answer 2

Is the answer 5%?

Answer 3

Yes, that is correct, well done.
It would be nice if you could get a more accurate table to get a number like 5.x%.