Question

Sunil started running around a circular track of length 1600m, from the starting point P. When Sunil reached 1200m mark, Ravi started running around the track from the point P, in the same direction as Sunil. When Ravi reached the 800 m marks, Rajesh started from point P, in the same direction as Ravi. When Rajesh reached the 400 m mark, Suresh started the point A, in the same direction as Rajesh. If when Sunil reached A for the first time, Ravi, Rajesh and Suresh also reached A for the first time, what is the ratio of the speeds of Sunil, Ravi, Rajesh and Suresh?
1. 3 : 12 : 24 : 32
2. 3 : 10 : 25 : 32
3. 1 : 3 : 6 : 12
4. 4 : 12 : 15 : 24
5. None of these

Answer 1

Correct Answer - Option 1 : 3 : 12 : 24 : 32

Concept used:

When the time is same, then the ratio of the speeds is the same as the ratio of distances covered by them.

CALCULATION :

When Sunil covers the last 400m, Ravi completes 1600m.

∴ The ratio of the speeds of Sunil and Ravi = 400: 1600 = 1 : 4

In the same way, when Ravi covers the last 800m, Rajesh completes 1600m.

∴ The ratio of the speed of Ravi and Rajesh = 800: 1600 = 1 : 2

In the same way, when Rajesh covers the last 1200m, Suresh completes 1600m

∴ The ratio of the speed of Rajesh and Suresh = 1200: 1600 = 3 : 4

The ratio of speeds -

Sunil : Ravi = 1 : 4 = 3 : 12

Ravi: Rajesh = 1 : 2 = 12 : 24

Rajesh: Suresh = 3 : 4 = 24 : 32

∴ The required ratio of speeds is 3 : 12 : 24 : 32.