CHAPTER 5 TEST ANSWERS
1.
6
or 0.4
15
2. Germaine’s probability of winning is
8
or about 0.62. Gabriel’s probability of
13
7
or about 0.64. Gabriel should start because his record is better.
11
3. a) Let R represent serving rice. Let C represent serving carrots.
winning is
b) P(R  C) = 0.22
4. The number of ways of selecting 7 spades from a deck of cards is 13C7.
The number of ways of selecting any 7 cards from a deck of cards is 52C7.
C7
52 C7
1716
or about 0.000 012 8
P(7 spades) =
133 784 560
5. Assume that the 3 books are arranged as a group. There are 7 other books, so I can
arrange 8 objects as 8P8, or 8! I can also arrange the 3 books within their group as 3!
The total number of ways to arrange all 10 books is 10!
P(7 spades) =
13
8! 3!
10!
8! × 3 × 2 × 1
P(the three books are together) =
10 × 9 × 8!
6
1
P(the three books are together) =
or
90 5
æ7ö æ6ö
6. a) P(2 red) = ç ÷ × ç ÷
è 12 ø è 11 ø
P(2 red) = 0.318… or about 0.32
P(the three books are together) =
æ5ö æ4ö
b) P(2 blue) = ç ÷ × ç ÷
è 12 ø è 11 ø
P(2 blue) = 0.151… or about 0.15
Copyright © 2012 by Nelson Education Ltd.
c) P(1 red, 1 blue) = 1 – P(2 blue) – P(2 red)
P(1 red, 1 blue) = 1 – 0.318… – 0.151…
P(1 red, 1 blue) = 0.530… or about 0.53
7. a) Let R represent walking by the river.
Let B represent walking around the block.
Let D represent seeing another dog.
b) P(see another dog) = 0.607… + 0.085… or 0.692…
Copyright © 2012 by Nelson Education Ltd.