The price of a good is the y-variable and the quantity of a good that people want to buy is the x-variable. When the price of a hamburger increases from $10 to $12, the quantity of hamburger that people want to buy in a day decreases from 20 to 16. What is the slope of the line that describes the relationship between price and the quantity of hamburgers that people want to buy?
A) -1/2
B) -2
C) -10
D) 5

Question

Quizplus · Accepted Answer

The slope of a line is calculated as the change in y over the change in x. Here, the change in price (y-variable) is $2 ($12 - $10), and the change in quantity (x-variable) is -4 (16 - 20). Thus, the slope = $2 / -4 = -1/2.

The Price of a Good Is the Y-Variable and the Quantity