Question

On average, Jamie can bike five times as fast as he can run. To travel 25 km, he needs 2 h more is he is running that is he is biking. What is his average running speed?

Answer 1

10 km/h

Explanation:

Let x km/h be Jamie's running speed. On average, Jamie can bike five times as fast as he can run, then Jamie's biking speed is 5x km/h.

Biking:

Distance = 25 km

Rate = 5x km/h

Time
`=(25)/(5x)` hours

Running:

Distance = 25 km

Rate = x km/h

Time
`=(25)/(x)` hours

To travel 25 km, Jamie needs 2 hours more when he is running than when he is biking.

Hence,

`(25)/(5x)+2=(25)/(x)\\ \\(5)/(x)+2=(25)/(x)\\ \\2=(25)/(x)-(5)/(x)\\ \\(25-5)/(x)=2\\ \\(20)/(x)=2\\ \\20=2x\\ \\x=10\ km/h`