Fuel economy estimates for automobiles built one year predicted a mean of 28.2 mpg and a standard deviation of 4.8 mpg for highway driving. Assume that a Normal model can be applied. Use the 68-95-99.7 Rule to complete parts a) through e).
a) Draw the model for auto fuel economy.
b) In what interval would you expect the central 68% of autos to be found?
Using the 68-95-99.7 rule, the central 68% of autos can be expected to be found in the interval from 23.4 mpg to 32.6 mpg. (Do not round. Type integers or decimals.)
c) About what percent of autos should get more than 33 mpg?
Using the 68-95-99.7 rule, about 31.85% of autos should get more than 33 mpg. (Do not round. Type an integer or a decimal.)
d) About what percent of autos should get between 33 and 37.8 mpg?
Using the 68-95-99.7 rule, about 34.13% of autos should get between 33 and 37.8 mpg. (Do not round. Type an integer or a decimal.)
e) Describe the gas mileage of the best 2.5% of cars.
Choose the correct answer below.
A. They get more than 42.6 mpg.
B. They get more than 33 mpg.
C. They get more than 37.8 mpg.
D. They get less than 23.4 mpg.