Bluebook SAT Test Two-Variable Data: Models and Scatterplots 11

Question 1

A scatterplot shows data about car speed (x, mph) and fuel efficiency (y, mpg). The line of best fit is y = −0.3x + 55. Predict fuel efficiency at 80 mph.

Accepted Answer

31 mpg

Answer

y = −0.3(80)+55 = −24+55 = 31 mpg.

Question 2

Which of the following correlation coefficients indicates the strongest linear relationship?

Accepted Answer

r = −0.97

Answer

|−0.97| = 0.97 is the largest absolute value, indicating the strongest linear relationship.

Question 3

A scatterplot of age of used cars (x, years) vs. value (y, dollars) shows a negative linear trend. Which value of r is most plausible?

Accepted Answer

r = −0.82

Answer

A negative trend with relatively strong association corresponds to r ≈ −0.82.

Question 4

A quadratic model y = 2x² − 4x + 3 predicts production cost. What is the cost when x = 5?

Accepted Answer

33

Answer

y = 2(25)−4(5)+3 = 50−20+3 = 33.

Question 5

The line of best fit y = 7x − 14 describes hours of practice (x) and score improvements (y). For what number of hours does the model predict zero improvement?

Accepted Answer

2

Answer

Set 0 = 7x−14 → x = 2.

Bluebook SAT Practice Test

Bluebook SAT Practice Test

Bluebook SAT Test Two-Variable Data: Models and Scatterplots 11