Two men A and B start walking simultaneously from P to Q,

Home » Aptitude » Speed, Time and Distance » Question

Two men A and B start walking simultaneously from P to Q, a distance of 21 kms, at the speed of 3 km and 4 km an hour respectively. B reaches Q, returns immediately and meets A at R. Find the distance from P to R.

1. 22 km
2. 20 km
3. 16 km
4. 18 km

Correct Option: D

Let A and B meet after time t hours.

Distance covered by A in t hours = 3 t km.
Distance covered by B in t hours = 4 t km.
Total distance covered by A and B = (3t + 4t) km = 7 t km.
From the diagram we can see that the total distance covered by A and B is equal to twice the distance between P and Q.
∴ 7t = 2 × 21

t =	2 × 21	= 6 hours
	2

Distance PR = 6 × 3 = 18 km.