souvonik2k wrote:

John takes 20 min to walk every kilometer (km). David takes 16 min to walk every km. Both of them walk in a race. If David beat John by 240 meters (m), find the length of the race (in km)? (1 km = 1000 m)

A) 1

B) 1.2

C) 1.4

D) 1.5

E) 1.6

Speed of David is 1/16 km per min and speed of John is 1/20 km per min.

In the time it took David to complete

d km ( which is what we want to find John could cover only (d - .24) km

What is constant between John and David is the time t.

dist = speed * time

d = t/16 ( for David)

d' = t/20 ( for John)

d - d' = .24km as given...

So d - 16d/20 = 0.24

d ( 4/20) = 0.24

d = 0.24 * 5 = 1.2km

Hence Option B.

Please give Kudos if you liked the explanation

_________________

Regards,

Gladi

“Do. Or do not. There is no try.” - Yoda (The Empire Strikes Back)