Suppose the following are the city driving gas mileages of a selection of sport utility vehicles (suvs).

19, 20, 19, 20, 18, 21, 17, 19, 24, 23, 21, 21, 17, 20, 20, 18

a) find the sample standard deviation (rounded to two decimal places).

b) in what gas mileage range does chebyshev's inequality predict that at least 75% of the selection will fall? (enter your answer using interval notation. round your answers to two decimal places.)

c)what is the actual percentage of suv models of the sample that fall in the range predicted in part (b)? (round your answer to two decimal places.) which gives the more accurate prediction of this percentage: chebyshev's rule or the empirical rule?

a. chebyshev's rule
b. empirical rule