Question

The graph below shows the number of houses sold over x days. What is the average rate of change from day 2 to day 10?

A graph entitle House Sales shows Number of Days on the x-axis, from 0 to 12, and Number of Houses Sold on the y-axis, from 0 to 12. A line connects 5 points. The points are (0, 0), (2, 8), (6, 6), (10, 2), (12, 4).

Answer 1

The average rate of change from day 2 to day 10 is -0.75

Using the data given , the coordinates for the 2nd and 10th day are ;

• (2, 8) and (10, 2)

The rate of change is the slope of the line which is ;

• Change in y / change in x

Change in y : (2 - 8) = -6

Change in x : (10 - 2) = 8

The average rate of change is :

• -6/8 = -0.75

Hence, average rate of change within the period is -0.75