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[apstat] TPS 4e Test 10A Q1 (MCQ)
Posted:
Apr 13, 2012 12:22 AM


Dear all,
Being a new teacher to AP Stats. I was wondering if anyone can help me with this question.
A city planner is comparing traffic patterns at two different intersections. He randomly selects 12 times between 6 am and 10 pm, and he and his assistant count the number of cars passing through each intersection during the 10minute interval that begins at that time. He plans to test the hypothesis that the mean difference in the number of cars passing through the two intersections during each of those 12 times intervals is 0. Which of the following is appropriate test of the city planner?s hypothesis?
(a) Twoproportion ztest (b) Twosample ztest (c) Matched pairs ttest (d) Two proportion ttest (e) Twosample ttest
The answer given is (c) Matched pairs ttest but many of my students selected (e) Twosample ttest.
The book's explanation for (c) is;
The ?pairs? are the twelve sets of 10minute time intervals?one at each intersection. The parameter of interest is the mean difference between the number of cars at each intersection.
My students are saying that it's "different intersection" and also since it's in Chapter 10, it should be Twosample ttest. How can I further convince my students?
Thanks.
Peter
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