10/25/2015 AP Stats AP Stats Chapter 3 Review

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Please select a Team. 1.Packers 2.Bears 3.Vikings 4.Cowboys Response Grid Countdown 10

1. A study found correlation r = 0.61 between the sex of a worker and his or her income. You conclude that 1.Women earn more than men on the average. 2.Women earn less than men on average. 3.An arithmetic mistake was made; this is not a possible value of r. 4.This is nonsense because r makes no sense here. Countdown 10 Response Grid

2. A copy machine dealer has data on the number x of copy machines at each of 89 customer locations and the number y of service calls in a month at each location. Summary calculations give = 8.4, sx = 2.1, = 14.2, sy = 3.8, and r = What is the slope of the least squares regression line of number of service calls on number of copiers? None of these 5.Can’t tell from the information given Countdown 10 Response Grid

3. In the setting of the previous problem, about what percent of the variation in the number of service calls is explained by the linear relation between number of service calls and number of machines? 1.86% 2.93% 3.74% 4.None of these Countdown 5 Response Grid

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4. If dataset A of (x,y) data has correlation coefficient r = 0.65, and a second dataset B has correlation r = –0.65, then 1.The points in A exhibit a stronger linear association than B. 2.The points in B exhibit a stronger linear association than A. 3.Neither A nor B has a stronger linear association. 4.You can’t tell which dataset has a stronger linear association without seeing the data or seeing the scatterplots. Countdown 10 Response Grid

5. There is a linear relationship between the number of chirps made by the striped ground cricket and the air temperature. A least squares fit of some data collected by a biologist gives the model = x, 9 < x < 25, where x is the number of chirps per minute and is the estimated temperature in degrees Fahrenheit. What is the estimated increase in temperature that corresponds to an increase in 5 chirps per minute? 1.3.3°F °F °F °F °F Countdown 10 Response Grid 1.For each increas e of one point in perform ance rating, the raise will increas e on averag e by $2,000. For each increase of one chirp(x) in, the temperature will increase on average by 3.3. But, this line is for 9 < x < 25.

6. The equation of the least squares regression line for the points on the scatterplot below is = x. What is the residual for the point (4,7)? Countdown 15 Response Grid

7. Linear regression usually employs the method of least squares. Which of the following is the quantity that is minimized by the least squares process? Countdown 5 Response Grid

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8. A set of data relates the amount of annual salary raise and the performance rating. The least squares regression equation is = 1, ,000x where y is the estimated raise and x is the performance rating. Which of the following statements is not correct? 1.For each increase of one point in performance rating, the raise will increase on average by $2, This equation produces predicted raises with an average error of 0. 3.A rating of 0 will yield a predicted raise of $1, The correlation for the data is positive. 5.All of the above are true. Countdown 10 Response Grid

9. Which of the following would not be a correct interpretation of a correlation of r = –.30? a)The variables are inversely related. (b)The coefficient of determination is (c)30% of the variation between the variables is linear. (d)There exists a weak relationship between the variables. (e)All of the above statements are correct. Countdown 15 Response Grid

10.The following are resistant: (a)Least squares regression line (b)Correlation coefficient (c) Both the least square line and the correlation coefficient (d)Neither the least square line nor the correlation coefficient (e)It depends Countdown 10 Response Grid

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