Use the image to answer the question.
A coordinate plane shows the x-axis, labeled as hours, ranging from 0 to 6 in increments of 1 and the y-axis, labeled as gallons, ranging from 0 to 240 in increments of 20. A line segment joins four plotted points. The coordinates of the plotted points are left parenthesis 0 comma 200 right parenthesis, left parenthesis 1 comma 160 right parenthesis, left parenthesis 3 comma 80 right parenthesis, and left parenthesis 5 comma 0 right parenthesis.
The graph shows the number of gallons in a wading pool that is being drained. Using the points (1,160) and (3,80) as (x1,y1) and (x2,y2) , what is the rate of change in the number of gallons in the pool after each hour has passed?
(1 point)
Responses
140 gal./hr.
Start Fraction 1 over 40 End Fraction gal./hr.
40 gal./hr.
40 gal./hr.
−40 gal./hr.
negative 40 gal./hr.
−140 gal./hr.
The rate of change in the number of gallons in the pool after each hour has passed can be calculated by finding the difference in the y-coordinates and dividing it by the difference in the x-coordinates.
From point (1,160) to (3,80), the difference in y-coordinates is 160 - 80 = 80 and the difference in x-coordinates is 3 - 1 = 2.
Therefore, the rate of change is 80/2 = 40 gal./hr.
The correct answer is 40 gal./hr.