Amy surveyed the prices for a quart of a certain brand of motor oil. The sample data, in dollars per quart, is summarized in the table below.

Price per Quart (dollars) Number of Stores

1.99 2

2.09 6

2.19 10

2.29 13

2.39 9

2.49 3

(a) Find the mean and the standard deviation of the prices. (Round your answers to three decimal places.)

Mean$

standard deviation$

(b) What percent of the data lies within one standard deviation of the mean? (Round your answer to the nearest whole number.) %

(c) What percent of the data lies within two standard deviations of the mean? (Round your answer to the nearest whole number.) %