Suppose that the mean retail price per gallon of regular grade gasoline in the United States is $3.41 with a standard deviation of $0.10 and that the retail price per gallon has a bell-shaped distribution. (a) What percentage of regular grade gasoline sold between $3.31 and $3.51 per gallon? 1 % (b) What percentage of regular grade gasoline sold between $3.31 and $3.61 per gallon? 3 % (c) What percentage of regular grade gasoline sold for more than $3.61 per gallon? %