(b) What percentage of regular grade gasoline sold between $2.68 and $3.88 per gallon? Recall the following information about the empirical rule. Empirical Rule For data having a bell-shaped distribution: Approximately 68% of the data values will be within one standard deviation of the mean. Approximately 95% of the data values will be within two standard deviations of the mean. Almost all of the data values will be within three standard deviations of the mean. This is represented graphically below. Note that a value of 0 standard deviations corresponds to the mea mean. almost all -3 -2 -1 95% 68% 0 1 2 N Now we are to determine the percentage of gas that sold between $2.68 and $3.88 per gallon. It was already determined that $2.68 is 2 standard deviations below the mean of $3.48. How many standard deviations above the mean is $3.88?