Page 21 - Probability Demystified

10 CHAPTER 1 Basic Concepts

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c. P(number less than 1) = ¼ 0, since there are no numbers in the
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sample space less than 1.
3 1
d. P(number is an odd number) = ¼ , since 1, 3, and 5 are odd
numbers. 6 2

3. The sample space is 1, 2, 3, 4, 5, 6, 7, 8, 9.
3 1
a. P(number divisible by 3) = ¼ , since 3, 6, and 9 are divisible
by 3. 9 3
2
b. P(number greater than 7) = , since 8 and 9 are greater than 7.
4 9
c. P(even number) = , since 2, 4, 6, and 8 are even numbers.
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4. The sample space is HH, HT, TH, TT.
1
a. P(TT) = , since there is only one way to get two tails.
4 3
b. P(at least one head) = , since there are three ways (HT, TH, HH)
4
to get at least one head.
1
c. P(HH) = , since there is only one way to get two heads.
4
^
5. The sample space is A˘,2 ,3¨,4˘,5¯,6¨.
1
a. P(4˘)= .
6 3 1
b. P(red card) = ¼ , since there are three red cards.
6 2
2 1
c. P(club) = ¼ , since there are two clubs.
6 3
6. The sample space is red, blue, green, and white.
1
a. P(blue) = , since there is only one blue ball.
4
2 1
b. P(red or blue) = = , since there are two outcomes in the event.
4 2
0
c. P(pink) = ¼ 0, since there is no pink ball.
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7. The sample space consists of the letters in ‘‘computer.’’
1
a. P(t) = .
8 2 1
b. P(o or m) = ¼ .
8 4
0
c. P(x) = ¼ 0, since there are no ‘‘x’’s in the word.
8
3
d. P(vowel) = , since o, u, and e are the vowels in the word.
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