question 15

Assume a member is selected at random from the population represented by the graph. Find the probability that the member selected at random is from the shaded area of the graph. Assume the variable x is normally distributed.

Braking Distance of Mid-Sized Sedans

149

130

159

=146

=5.21

149

The probability that the member selected at random is from the shaded area of the graph is

. (Round to four decimal places asneeded.)

question 16

Use the normal distribution of SAT critical reading scores for which the mean is 506 and the standard deviation is 120. Assume the variable x is normally distributed.

(a)

What percent of the SAT verbal scores are less than 675?

(b)

If 1000 SAT verbal scores are randomlyselected, about how many would you expect to be greater than 575?

(a) Approximately _____ of the SAT verbal scores are less than 675.

(Round to two decimal places asneeded.)

b. ????

question 17

The total cholesterol levels of a sample of men aged35-44 are normally distributed with a mean of 215 milligrams per deciliter and a standard deviation of 37.5 milligrams per deciliter.

(a) What percent of the men have a total cholesterol level less than 218 milligrams per deciliter ofblood?

(b) If 241 men in the35-44 age group are randomlyselected, about how many would you expect to have a total cholesterol level greater than 253 milligrams per deciliter ofblood?

question 18

Use the normal distribution of fish lengths for which the mean is 8 inches and the standard deviation is 4 inches. Assume the variable x is normally distributed.

(a)

What percent of the fish are longer than 13 inches?

(b)

If 300 fish are randomlyselected, about how many would you expect to be shorter than 7 inches?

question 19

Use the standard normal table to find thez-score that corresponds to the given percentile. If the area is not in thetable, use the entry closest to the area. If the area is halfway between twoentries, use thez-score halfway between the correspondingz-scores. Ifconvenient, use technology to find thez-score.

P18

Thez-score that corresponds to P18 is

(Round to two decimal places asneeded.)