Page 155 - Probability Demystified

144 CHAPTER 8 Other Probability Distributions

8. Of the 20 automobiles in a used car lot, 8 are white. If 6 are selected
at random to be sold at an auction, the probability that exactly 2 are
white is
a. 0.267
b. 0.482
c. 0.511
d. 0.358
9. A board of directors consists of 7 women and 5 men. If a slate of
4 officers is selected at random, the probability that exactly 2 officers
are men is

a. 0.375
b. 0.424
c. 0.261
d. 0.388
10. The number of boating accidents on a large lake follows a Poisson
distribution. The probability of an accident is 0.01. If there are 500
boats on the lake on a summer day, the probability that there will be
exactly 4 accidents will be
a. 0.192
b. 0.263
c. 0.175
d. 0.082

11. About 5% of the population carries a genetic trait. Assume the dis-
tribution is Poisson. The probability that in a group of 100 randomly
selected people 7 people carry the gene is
a. 0.256
b. 0.104
c. 0.309
d. 0.172
12. When a coin is tossed, the probability of getting the first tail on the
fourth toss is

1
a.
2
3
b.
4