Question

A bicyclist rode a distance of 21 miles in 75 minutes. What was her speed in miles per hour?

Answer 1

A bicyclist rode a distance of 21 miles in 75 minutes. What was her speed in miles per hour?

Step 1

Let

1 hour =60 min

Step 2

using a rule of three, convert 75 minutes into hours

if

`\begin{gathered} 60\text{ min}\Rightarrow1\text{ hour} \\ 75\text{ min }\Rightarrow\text{ x hour} \end{gathered}`

the relaton is

`\begin{gathered} (60)/(1)=(75)/(x) \\ \text{solve for x} \\ 60x=75 \\ x=(75)/(60) \\ x=1.25 \end{gathered}`

then, 75 minutes = 1.25 hours

Step 3

find the speed

Let

distance=21 miles

time=1.25 hours

`\begin{gathered} \text{speed}=\frac{dis\tan ce}{\text{time}}=\frac{21\text{ miles}}{1.25\text{ hours}} \\ \text{speed}=16.8\text{ miles per hour} \end{gathered}`

so, the answer is 16.8 miles per hour