please help

[ticka06]

12. 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?

 

[galactus]

Just use $\displaystyle z=\frac{x-{\mu}}{\sigma}$

Look them up in the z-table and subtract the values.

$\displaystyle z=\frac{161.28-138}{9.7}=2.4$

$\displaystyle z=\frac{164.9-138}{9.7}=2.77$

Look them up and subtract.