Purse Snatching. The Federal Bureau of Investigation (FBI) compiles information on robbery and property crimes by type and selected characteristic and publishes its findings in Uniform Crime Reports. According to that document, the mean value lost to purse snatching was in . For last year, randomly selected purse-snatching offenses yielded the following values lost, to the nearest dollar.
Use a t-test to decide, at the significance level, whether last year's mean value lost to purse snatching has decreased from the mean. The mean and standard deviation of the data are and , respectively.
There is insufficient data to support the allegation that the mean value of purses stolen last year was lower than in .
The facts to come to a conclusion about the previous year's mean.
According to the document, the average amount stolen due to handbag snatching in was. Last year, purse-snatching offences were chosen at random and the following values were lost, to the nearest dollar.
Use a t-test to determine whether the mean value lost to purse snatching last year was lower than the mean at the significance level. The data has a mean and standard deviation of and , respectively.
Refer to Exercise 9.19. Explain what each of the following would mean.
(a) Type I error.
(b) Type II error.
(c) Correct decision.
Now suppose that the results of carrying out the hypothesis test lead to the rejection of the null hypothesis. Classify that conclusion by error type or as a correct decision if in fact the mean length of imprisonment for motor-vehicle-theft offenders in Sydney.
(d) equals the national mean of 16.7 months.
(e) differs from the national mean of 16.7 months.
Data on salaries in the public school system are published annually in Ranking of the States and Estimates of School Statistics by the National Education Association. The mean annual salary of (public) classroom teachers is thousand. A hypothesis test is to be performed to decide whether the mean annual salary of classroom teachers in Ohio is greater than the national mean.
Cheese Consumption. Refer to Problem . The following table provides last year's cheese consumption: in pounds, 35 randomly selected Americans.
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