Question

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

Answer 1

Answer: Running speed is 10k/h

Biking speed is 50k/h

Step-by-step explanation:

My procedure may be unconventional, but it works:

Compute the time it takes, then translate to speed. 25k at biking speed takes 2 hours less than at running speed which is 1/5 bike speed.

Distance/speed = time  25/x=25/(5x-2)  cross multiply divisors

25(5x-2) = 25x  ==> 125x -50 =25x ==>  100x = 50  

x = 0.5 hours at biking speed   25k/0.5h = 50k/h  

Running speed = 50/5  10k/h

Proof: 25k/ 10k/h = 2.5 hours

25k /50k/h = 0.5 hours  

2.5 h - .5 h = 2 hours, the difference stated in the question.