Introduction To Probability And Statistics
15th Edition
ISBN: 9781337554428
Author: Mendenhall, William.
Publisher: Cengage Learning,
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Chapter 5, Problem 10RWYL
Psychosomatic Problems A psychiatrist believesthat 80% of all people who visit doctors have problemsof a psychosomatic nature. She decides to select 25patients at random to test her theory.
- Assuming that the psychiatrist’s theory is true, whatis the
expected value of x. the number of the 25patients who have psychosomatic problems? - What is the variance of x, assuming that the theoryis true? Find
- (Use tables and assume that thetheory is true.)
- Based on the
probability in part e, if only 14 of the25 sampled had psychosomatic problems. What conclusions would you make about the psychiatrist’s theory? Explain.
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why the answer is 3 and 10?
PS
9 Two films are shown on screen A and screen B at a cinema each evening. The numbers
of people viewing the films on 12 consecutive evenings are shown in the back-to-back
stem-and-leaf diagram.
Screen A (12) Screen B (12)
8
037
34
7 6 4 0 534
74 1645678
92 71689
Key: 116|4 represents 61 viewers for A and 64 viewers for B
A second stem-and-leaf diagram (with rows of the same width as the previous diagram)
is drawn showing the total number of people viewing films at the cinema on each of
these 12 evenings. Find the least and greatest possible number of rows that this second
diagram could have.
TIP
On the evening when 30 people viewed films on screen A, there could have been as few
as 37 or as many as 79 people viewing films on screen B.
Q.2.4 There are twelve (12) teams participating in a pub quiz. What is the probability of correctly predicting the top three teams at the end of the competition, in the correct order? Give your final answer as a fraction in its simplest form.
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Introduction To Probability And Statistics
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