Question

nes ing Online book David's dad drove at a constant rate for 25 miles. It took him 20 minutes. At what rate was David's dad driving (in miles per hour)? 55 miles per hour 65 miles per hour 75 miles per hour ps 85 miles per hour #

Answer 1

In order to calculate the rate (that is, the speed) David's dad was driving in miles per hour, first let's convert the time from minutes to hours using a rule of three:

`\begin{gathered} 1\text{ hour}\to60\text{ minutes} \\ x\text{ hours}\to20\text{ minutes} \\ \\ 60x=20\cdot1 \\ x=(20)/(60)=(1)/(3) \end{gathered}`

Now, to find the speed, we just need to divide the distance by the time:

`\text{speed}=(25)/((1)/(3))=25\cdot3=75\text{ mph}`

So the speed is 75 mph, therefore the answer is the third option.