Chapter 4.3, Problem 15E

The normal monthly rainfall in Seattle, Washington, is given in Figure $4.85$.

Month	Jan.	Feb.	Mar.	Apr.	May	June
$\text{inches}$	$5.4$	$4.0$	$3.8$	$2.5$	$1.8$	$1.6$

Month	Jan.	Feb.	Mar.	Apr.	May	June
$\text{inches}$	$5.4$	$4.0$	$3.8$	$2.5$	$1.8$	$1.6$

Figure $4.85$ Monthly rainfall in Seattle, Washington. Source: U.S. Department of Commerce.

a. Find the mean and standard deviation of the monthly rainfall in Seattle.

b. What percent of the year will the monthly rainfall be within one standard deviation of the mean?

c. What percent of the year will be the monthly rainfall be within two standard deviations of the mean?