Question

If Jeff continues to read at the same rate as shown in the graph, how many hours would it take him to read 90 pages?

Answer 1

To determine the time it will take Jeff to read 90 pages, the first step is to calculate the rate of change using the formula of the slope

`m=(y_2-y_1)/(x_2-x_1)`

Using the points (1,20) and (3,60)

`\begin{gathered} m=(60-20)/(3-1) \\ m=(40)/(2) \\ m=20 \end{gathered}`

This means that Jeff reads 20 pages per hour.

The relationship between both variables is direct

`\begin{gathered} y=mx \\ y=20x \end{gathered}`

Using this expression you can calculate the time it will take him you read 90 pages, replace the equation with y=90

`90=20x`

Divide both sides by 20

`\begin{gathered} (90)/(20)=(20x)/(20) \\ 4.5=x \end{gathered}`

It will take him 4.5 hours to read 90 pages.