Suppose that the average length of telephone calls made by teenagers is a normally distributed variable...

Suppose that the average length of telephone calls made by teenagers is a normally distributed variable with mean and standard deviation given in columns 1 and 2 of Table B (LAB4B.DAT).

mean: 42.6

standard deviation: 17.96

8. What is the probability that a random telephone call will last a length of time that is within one standard deviation of the mean (± 1 standard deviation)?

9. What is the proportion of telephone calls that last a length of time that is within two standard deviations of the mean (± 2 standard deviations)?

10. What is the relative frequency of lengths of teenage telephone calls that lie within three standard deviations of the mean (± 3 standard deviations)?

11. What is the probability that a telephone call will be longer than the mean by more than 1.645 standard deviations?

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8. What is the probability that a random telephone call will last a length of time that is within one standard deviation of the mean (± 1 standard deviation)?

9. What is the proportion of telephone calls that last a length of time that is within two standard deviations of the mean (± 2 standard deviations)?

10. What is the relative frequency of lengths of teenage telephone calls that lie within three standard deviations of the mean (± 3 standard deviations)?

11. What is the probability that a telephone call will be longer than the mean by more than 1.645 standard deviations?

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orchestra answered 2 years ago

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