Having started from the same point and at the same time, two runners - P and Q - are running around a circular track of length 500 m in opposite directions with the speeds of 6 m/s and 10 m/s, respectively. If they exchange their speeds after meeting for the first time, who will reach the starting point first?

Question

Question

This question was previously asked in

SSC CGL 2023 Tier-I Official Paper (Held On: 25 Jul 2023 Shift 4)

Answer 1

Given:

Total circular track length = 500 m

Speed of P = 6 m/s

Speed of Q = 10m/s

Formula used:

Distance = relative speed × time

Calculation:

Distance = relative speed × time

⇒ 500 = (10 + 6) × time

⇒ Time = 500/16 = 125/4 = 31.25 sec

Distance covered by P = 6 × 31.25 = 187.5 m

Distance covered by Q = 10 × 31.25 = 312.5 m

If speeds of P and Q are exchanged then

Time taken by P to cover 312.5 m = 312.5/10 = 31.25 sec

Time taken by Q to cover 187.5 m = 187.5/6 = 31.25 sec

Since the time is same. So P and Q reach the starting point at the same time.

∴ The correct option is 3.

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