Question

The graph shows the number of emails sent per day plotted against the number of hours sanchita works on a computer per day. Find the estimate of the average rate of change in the number of emails sent per day by sanchita compared to the number of hours spent by her on computer?

• A. $0.12$
• B. $1.5$
• C. $8.5$
• D. $12$

Answer 1

The correct option is C $8.5$

$\Rightarrow$ When real-world data is presented in a scatterplot, the average rate of change is the same as the slope of the best-fit line.

$\Rightarrow$ Find the slope of the best-fit line using the slope formula, $m=\frac{y_2-y_1}{x_2-x_1}$ and any two points that lie on (or very close to) the line.

$\Rightarrow$ Using the two points $(4,46)$ and $(8,80)$.

$\Rightarrow$ The average rate of change is about $=\frac{80-46}{8-4}=\frac{34}{4}=8.5$