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AP Statistics / Mr. Hansen |
Name: ___________________________ |
Part IV: The 20-Year Curriculum Short Answers (5 points each)
16. We say that an observed difference is statistically significant iff ___________________________________________________________________ .
17. Sheriff Jimmy (Judge Jeremy’s brother) says that before he took office, the crime rate was high. Now, 4 years later, he is running for re-election and proudly cites statistics showing that the crime rate is down noticeably in nearly all categories. As you might expect, Sheriff Jimmy claims that he is the cause of these improvements. Criticize his logic, please.
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Part V: Free Response (points in parentheses)
18 (6 pts.). Judge Jeremy, after his stellar career in law enforcement, decided to retire and become a statistics teacher. One day he asked his students to produce a LSRL residual plot, and one of the students produced the diagram shown below. How did Judge Jeremy know that the student had made a mistake? (I am not asking whether the residual plot is "good" or "bad." I am asking why it is impossible.)
19. See below for a data set showing various speeds measured for a certain small boat, and the horsepower that went into the generation of the boat’s wake. In other words, this would be the (essentially wasted) horsepower used to overcome the turbulence and water resistance of the water that the boat has to go through. This horsepower figure increases very sharply as speed increases.
|
Speed (mph) |
10 |
15 |
17.5 |
22 |
23.8 |
28 |
31 |
|
Wake horsepower (hp) |
0.103 |
1.71 |
5 |
25 |
43.3 |
133 |
272 |
(a)(6 pts.) Indicate which variable is explanatory and which is response.
(b)(10 pts.) Develop a linear model for associating speed and wake horsepower. Important: You must justify why your model is not appropriate, using at least two supporting pieces of evidence (one for partial credit).
(c)(6 pts.) Use your model to predict wake horsepower when the boat’s speed is 30 mph. Show your work.
(d)(6 pts.) State the y-intercept and interpret it in the context of the problem.
(e)(6 pts.) State the slope and interpret it in the context of the problem.
(f)(10 pts.) State values and
provide the name (in English) for r and r2 here.