Suppose that water usages in American showers are normally distributed, with an average shower using 15.2 gallons, and a standard deviation of 3 gallons. Estimated the percentage of showers that used...

Suppose that water usages in American showers are normally distributed, with an average shower using 15.2 gallons, and a standard deviation of 3 gallons. Estimated the percentage of showers that used

a. between 9.2 and 21.2 gallons.

______%

b. more than 18.2 gallons.

______%

c. less than 9.2 gallons.

______%

d. between 6.2 and 21.2 gallons.

______%