Some employers use lie detector tests to screen job applicants. Lie detector tests are not completely
reliable. Suppose that in a lie detector test, 65 of lies are identified as lies and that 14 of true
statements are also identified as lies.
A company gives its job applicants a polygraph test, asking Did you tell the truth on your job
application?. Suppose that 93 of the job applicants tell the truth during the polygraph test.
What is the probability that a person who fails the test was actually telling the truth?
A) 0.259 B) 0.349 C) 0.14 D) 0.741
Q. 222.6 16.1 36.1 36.0 23.8 20.3
A) 36.1 B) 4347.7 C) 3999.0 D) 8.35
Q. 3The number of hours per day a college student spends on homework has a mean of 6 hours and a
standard deviation of 1.25 hours. Yesterday she spent 3 hours on homework. How many standard
deviations from the mean is that?
A) 1.20 standard deviations below the mean B) 1.20 standard deviations above the mean
C) 2.40 standard deviations below the mean D) 2.40 standard deviations above the mean
Q. 4Scores on a test have a mean of 66 and a standard deviation of 9. Michelle has a score of 57.
Convert Michelle's score to a z-score.
A) 1 B) -9 C) 9 D) -1
Q. 5If a person told you in what month he was born, would it be unusual to guess the date of his
birth (not including the year)?
A) Yes B) No
Q. 6The annual snowfall in a town has a mean of 35 inches and a standard deviation of 11 inches. Last
year there were 60 inches of snow. How many standard deviations from the mean is that?
A) 2.27 standard deviations above the mean B) 0.40 standard deviations below the mean
C) 0.40 standard deviations above the mean D) 2.27 standard deviations below the mean
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