9 The quantitative data set under consideration has roughly abell-shaped distribution. Apply the empirical rule to answer the following question.

A quantitative data set has mean 20 and standard deviation 3. Approximately what percentage of the observations lie between 11 and 29?

Approximately ( ? ) % of the observations lie between 11 and 29.

(Type an integer or a decimal. Round to one decimal place asneeded.)

10 The probability is 0.45 that a traffic fatality involves an intoxicated oralcohol-impaired driver or nonoccupant. In ten trafficfatalities, find the probability that thenumber, Y, which involve an intoxicated oralcohol-impaired driver or nonoccupant is

a. exactlythree; at leastthree; at most three.

b. between two and four, inclusive.

c. Find and interpret the mean of the random variable Y.

d. Obtain the standard deviation of Y.

12 Construct astem-and-leaf diagram for the accompanyingdata, using two lines per stem.

(Use ascendingorder.)

20

49

31

40

42

31

29

30

27

45

30

28

44

43

41

42

26

39

49

32