Page 156 - Probability Demystified

CHAPTER 8 Other Probability Distributions 145

1
c.
8
1
d.
16

13. An eight-sided die is rolled. The average number of tosses that it will
take to get a 6 is
a. 6
b. 16
c. 8
d. 12
14. A ten-sided die is rolled; the average number of tosses that it will take
to get three 3s is
a. 30
b. 8
c. 18
d. 40

15. On average how many rolls of an eight-sided die will it take to get all
the faces at least once?

a. 28.62
b. 64
c. 21.74
d. 32

Probability Sidelight

SOME THOUGHTS ABOUT LOTTERIES

Today we are bombarded with lotteries. Almost everyone has the fantasy of
winning mega millions for a buck. Each month the prizes seem to be getting
larger and larger. Each type of lottery gives the odds and the amount of the
winnings. For some lotteries, the amount you win is based on the number of
people who play. However, the more people who play, the more chance there
will be of multiple winners.
The odds and the expected value of a lottery game can be computed using
combinations and the probability rules. For example, a lottery game in
Pennsylvania is called ‘‘Match 6 Lotto.’’ For this game, a player selects