Page 251 - Probability Demystified

240 FINAL EXAM

46. The scores on a national achievement test are approximately nor-
mally distributed with a mean of 120 and a standard deviation of
10. The probability that a randomly selected student scores between
100 and 130 is

a. 68.2%
b. 34.1%
c. 48.8%
d. 81.8%

47. The heights of a group of adult males are approximately distributed
with a mean of 70 inches and a standard deviation of 2 inches. The
probability that a randomly selected male from the group is between
68 and 72 inches is
a. 34.1%
b. 68.2%
c. 81.8%
d. 95.4%
48. The average time it takes an express bus to reach its destination is
32 minutes with a standard deviation of 3 minutes. Assume the vari-
able is normally distributed. The probability that it will take the bus
between 30.5 minutes and 33.5 minutes to arrive at its destination is

a. 38.3%
b. 93.3%
c. 34.1%
d. 6.7%
49. The average time it takes pain medicine to relieve pain is 18 minutes.
The standard deviation is 4 minutes. The variable is approximately
normally distributed. If a randomly selected person takes the medica-
tion, the probability that the person experiences pain relief within
25.2 minutes is

a. 50%
b. 68.3%
c. 75.2%
d. 96.4%