The average amount of rainfall in Puerto Rico last month was 3.5 inches, according to the National Meteorology Center. Suppose that a normal distribution can be used and that the standard deviation is...

The average amount of rainfall in Puerto Rico last month was 3.5 inches, according to the National Meteorology Center. Suppose that a normal distribution can be used and that the standard deviation is 0.8 inches.

a) What percentage of the time was last month's rainfall greater than 5 inches?
b) What percentage of the time was rainfall less than 3 inches?
c) A month is considered extremely humid if the rainfall is 10% higher for that month. How much rainfall must be in April to be considered an extremely humid month?