Rate of change: graphs

Question

Beth kept a tally of the number of emails she received each day for a week.

emails beths receive

7

6

5

4

3

2

1

0

Sunday Monday Tuesday Wednesday Thursday

According to the graph, what was the rate of change between Wednesday and Thursday?

emails per day

Answer 1

The average rate of change between any two points is the slope of the line connecting the points. For any two points, (x₁,y₁) and (x₂,y₂), the slope formula is:

m = (y₂-y₁) / (x₂-x₁)

In your case, the y's are the number of emails and the x's are the days. So:

rate of change = (Number of emails on Thursday - Number of emails on Wednesday) / (1 day)

Since Wednesday to Thursday is 1 day. I can't tell from your table how the days and emails line up, but you can read it and insert the correct numbers into the above formula to get the answer.