In each of the following settings, decide whether you should use two-sample procedures for a difference in proportions, two-sample procedures for a difference in means, or paired procedures for a mean difference.

(a.) A city planner is comparing traffic patterns at two different intersections. He randomly selects 12 times between 6:00 a.m. and 10:00 p.m., and he and his assistant count the number of cars passing through each intersection during the 10-minute interval that begins at that time.

Two-sample test for 12

Two-sample test for 12

Two-sample test for 12

Paired test for diff

(b). How much greater is the proportion of senior citizens who attend a play at least once per year than the proportion of 20-somethings who do so? Random samples of 100 senior citizens and 100 people in their 20s were surveyed.

Two-sample test for 12

Two-sample test for 12

Two-sample test for 12

Two-sample test for 12

(c). Luke's taco shop is considering a switch to a new tortilla that supposedly has a larger diameter. To test this claim, Luke takes a random sample of 50 of the old tortillas and 50 of the new tortillas and records the diameter of each.

Two-sample test for 12

Two-sample test for 12

Paired test for diff

Two-sample test for 12