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

My approach is :

John takes 20 min to walk 1000m

David takes 16 min to walk 1000m

let's calculate the distance John walks in 16 min : 16 *1000 / 20 = 800m, this means that John will loose 200m every 1000m which David walks.

Since David won the race by 240m, and given the ratio john's distance lost to David distance walked, we can easily determine total length of the race : 240 * 1000 / 200 = 1200 (1.2km) Answer B

Hope it helps