Chapter 8, Problem 28PT

To determine

To find: How many hours it would take her to bike 80 miles.

Answer to Problem 28PT

It would take her 4 hours to bike 80 miles.

Explanation of Solution

Given information:

The distance that Susan travels varies directly with the amount of time she is biking and she bikes 50 miles in 2.5 hours.

Calculation:

Since, since the distance varies directly with the amount of time. Therefore,

  $\begin{array}{l}\frac{50}{2.5}=\frac{80}{y}\text{ (Direct variation)}\\ 50y=80\cdot \left(2.5\right)\text{ (Cross multiply)}\\ 50y=200\text{ (Simplify)}\\ y=\frac{200}{50}\text{ (Divide each sides by 50)}\\ y=4\text{ hours}\end{array}$

Hence,

It would take her 4 hours to bike 80 miles.