Choosing Which Significance Test AP Stats

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A factory manager would like to compare two different assembly techniques by looking at the average number of units assembled by an employee during a certain time period. The manager uses random selection to choose 200 employees from the factory, and randomly assigns each employee to one of the two techniques. After training the employees on their respective techniques, the manager records the number of units each of the employees assembles within the allotted time. Which of the following would be the most appropriate inferential statistical test in this situation?

• One-sample z-test

• Two-sample t-test

• Paired t-test

• One-sample t-test

• None of these tests are appropriate

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A box of Raspberry Crunch cereal contains a mean of 13 ounces with a standard deviation of 0.5 ounces.  The distribution of the contents of cereal boxes is approximately Normal.  The cereal company is afraid the boxes being over filled.  Suppose they get a random sample of 25 boxes, and find a mean of 13.2 and a standard deviation of 0.154.  Does this give evidence that the boxes are being overfilled?

• sample t-test

• sample t-test

• proportion z-test

• chi-squared GOF test

A random sample of 49 medical doctors in LA showed that they worked an average of 53.1 hours/week with a standard deviation of 7.2 hours/week.  If the California average is 60 hours/week, does this give evidence that the LA doctors work significantly less than the rest of California?

• sample t-test

• sample t-test

• proportion z-test

• proportion z-test

USA Today reported that in 1992, 39% of all elementary school children claimed that when they grow up they want to do something to help other people.  However, in 1995, 128 of a random sample of 317 of these same children claimed that when they grow up they want to do something to help other people.  Does this information indicate that there has been an attitude change either way?

• proportion z-test

• proportion z-test

• sample t-test

• sample t-test

The manager of a sporting goods store offered a bonus commission to his salespeople when they sold more goods.  A new manager dropped the bonus system.  For a random sample of six sales, the weeks sales (in thousands of dollars) were 3.7 with the bonus, SD of .15, and 3.3 without the bonus, SD of .21.  Does this imply that sales dropped when the bonus system was discontinued?

• sample t-test

• sample t-test

• proportion z-test

• proportion z-test