Suppose that the mean retail price per gallon of regular grade gasoline in the United States is $3.43 with a standard deviation of $0.20 and that the retail price per gallon has a bell-shaped distribution.

a. What percentage of regular grade gasoline sold between $3.23 and $3.63 per gallon?

b. What percentage of regular grade gasoline sold between $3.23 and $3.83 per gallon? c. What percentage of regular grade gasoline sold for more than $3.83 per gallon? %