Bluebook SAT Test Two-Variable Data: Models and Scatterplots 7

Question 1

A model for monthly sales (y) based on marketing spend (x, hundreds of dollars) is y = 12x + 80. How many units are sold when $500 is spent on marketing?

Accepted Answer

140

Answer

x = 5 (hundreds): y = 12(5) + 80 = 60 + 80 = 140.

Question 2

The data points (1, 3), (2, 6), (3, 9), (4, 12) lie exactly on a line. What is the slope of the best-fit line?

Accepted Answer

3

Answer

The y value increases by 3 for each unit increase in x, so slope = 3.

Question 3

A dataset has a line of best fit y = −0.5x + 100. When x = 0, what is y? When x = 100, what is y?

Accepted Answer

y = 100 when x = 0; y = 50 when x = 100

Answer

At x = 0: y = 100; at x = 100: y = −0.5(100) + 100 = −50 + 100 = 50.

Question 4

A researcher collects data and finds the second differences of y are approximately constant. What type of model fits best?

Accepted Answer

Quadratic

Answer

Constant second differences are the hallmark of a quadratic (second-degree polynomial) model.

Question 5

The correlation coefficient between hours of TV watched and GPA is r = −0.73. What can you conclude?

Accepted Answer

Students who watch more TV tend to have lower GPAs, and the relationship is moderately strong

Answer

r = −0.73 indicates a moderately strong negative association; correlation doesn't establish causation.

Bluebook SAT Practice Test

Bluebook SAT Practice Test

Bluebook SAT Test Two-Variable Data: Models and Scatterplots 7