Chapter 3A Review

1. Other things being equal, larger automobile engines consume more fuel efficient. You are planning an experiment to study the effect of engine size (in liters) on the gas mileage (in miles per gallon) of sport utility vehicles. In this study,

1. Other things being equal, larger automobile engines consume more fuel efficient. You are planning an experiment to study the effect of engine size (in liters) on the gas mileage (in miles per gallon) of sport utility vehicles. In this study,

A) gas mileage is a response variable and you expect to find a negative association

2. In a statistics course, a linear regression equation was computed to predict the final-exam score from the score on the first test. The equation was yhat = 10 + 0.9x where y is the final-exam score and x is the score on the first test. Carla scored 95 on the first test. What is the predicted value of her score on the final exam?

D) 95.5

3. In the course decribed in #2, Bill scored a 90 on the first test and a 93 on the final exam. What is the value of his residual?

B) 2.0 (93-91) (y-yhat)

4. The correlation between the heights of fathers and the heights of their (fully grown) sons is r = 0.52. This value was based on both variables being measured in inches. If fathers' heights were measured in feet (one foot equals 12 inches), and sons' heights were measured in furlongs (one furlong equals 7920 inches), the correlation between heights of fathers and heights of sons would be

C) unchanged: equal to 0.52

5. All but one of the statements contain an error. Which is correct?

E) The correlation between mid-August soil moisture and the per acre yield of tomatoes is r= 0.53

6. A least-squares regression line for predicting weights of basketball players on the basis of their heights produced the residual plot below. What does the residual plot tell you about the linear model?

C) The curved pattern in the residual plot suggests that the linear model is not appropriate.

7. A community college announces that the correlation between college entrance exam grades and scholastic achievement is -1.08

E) the college should hire a new statistician

8. An agricultural economist says that the correlation between corn prices and soybean prices is r=0.7

A) When corn prices are above average, soybean prices also tend to be above average

10. There is an approximate linear relationship between the heights of females and their age (from 5 to 18 years) described by the equation height = 50.3 +6.1(Age), where height is measured in centimeters and age in years

A) The estimated slope is 6.1, which implies that female children between the ages of 5 and 18 increase in height by about 6.1 cm for each year they grow

11. You are interested in predicting the cost of heating houses on the basis of how many rooms the house has. A scatterplot of 25 houses reveals a strong linear relationship between these variables, so you calculate a least squares regression line. "Least squares" refers to

E) Minimizing the sum of the squares of the residuals

12. Leonardo da Vinci....

A) If one if the students in the sample had a height of 70 inches and an armspand of 68 inches, then the residual for this student would be about -2.36

13. If bivariate data set A has correlation r= 0.95 and a second bivariate data set B has correlation r= -0.95, then

D) you can't tell whether either data set is best described by a linear model until you examine the scatterplots

14. A regression of the amount of calories in a serving of breakfast cereal vs. the amount of fat gave the following results: Predicted calories= 97.1053 + 9.6525(Fat). Which of the following is false?

E) If one cereal has 140 calories and 5 g of fat. It's residual is about 5 inches

15. A copy machine dealer has data pn the number of copy machines x at each of 89 customer locations and the number of service calls in a month y at each location. Summary calculations give x= 8.4, y= 14.2, s= 3.8, and r= 0.86. What is the slope of the least squares regression line of number service calls on number of copiers?

B) 1.56

16. In the setting of the previous problem, about what percent of the variation in the number of services calls is explained by the linear relation between number of service calls and number of machines?

C) 74%

17. A study examined the relationship between the sepal length and sepal width for two varieties of an exotic tropical plant. Varieties X and O are represented by x's and o's respectively

D) Considering each variety separately, there is a negative correlation between sepal length and width

18. Mr. Nerdly asked the students in his AP Statistics class to report their overall grade point averages and their SAT Math scores. The scatterplot below provides information about his student's data. The dark line is the least squares...

E) Removing this student's data point would decrease the slope of the least-squares line

19. The circled point represents a roller coaster in the Philippines whose maximum height is 70 ft. The observed speed of this roller coaster is closest to:

D) 55 mph

20. Which of the following best describes what s=10.5371 represents the setting

E) The standard deviation of the residuals-- observed height minus predicted height