As determined from long experience, the number of automobiles rented per hour, X, at the Rent-A Car counter at Honolulu International Airport has the following probability distribution.

Automobiles Rented Probability

0 .10

1 .25

2 .45

3 "a"

4 .05

Calculate the standard deviation.

A. 0.96 B. 0.97 C. 0.98 D. 0.99 E. none of the above

A lot has 10% defective items. Ten items are chosen randomly. The probability that exactly 2 of the items are defective is:

A. 0.0036 B. 0.1937 C. 0.2234 D. 0.3874