question 19

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.

SAT Critical Reading Scores

200

400

800

=502

=123

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

(Round to four decimal places asneeded.)

question 20

In a survey of a group ofmen, the heights in the20-29 age group were normallydistributed, with a mean of 67.8 inches and a standard deviation of 4.0 inches. A study participant is randomly selected. Complete parts(a) through(d) below.

(a) Find the probability that a study participant has a height that is less than 68 inches.

The probability that the study participant selected at random is less than 68 inches tall is _______ (Round to four decimal places asneeded.)

(b) Find the probability that a study participant has a height that is between 68 and 71 inches.

The probability that the study participant selected at random is between 68 and 71 inches tall is _______ (Round to four decimal places asneeded.)

(c) Find the probability that a study participant has a height that is more than 71 inches.

The probability that the study participant selected at random is more than 71 inches tall is _____

(Round to four decimal places asneeded.)

(d) Identify any unusual events. Explain your reasoning. Choose the correct answer below.

A.

The event in part (a) is unusual because its probability is less than 0.05.

B.

The events in parts (a)and(c) are unusual because its probabilities are less than 0.05.

C.

Theeventsinparts(a),(b),and(c)areunusualbecausealloftheirprobabilitiesareless than 0.05.

D.

Therearenounusualeventsbecausealltheprobabilitiesaregreater than 0.05.