Question

Two friends P and Q start travelling simultaneously from X and Y respectively with their speeds differing by 120 km/h. They would meet at A where XA = 140 km and AY = 20 km. If they continue travelling to and from between X and Y until they meet for the second time, after how many hours do they meet for the second time?
1. 2 hours
2. 3 hours
3. 4 hours
4. 5 hours

Answer 1

Correct Answer - Option 2 : 3 hours

Given:

XA = 140 km, AY = 20 km

Concept:

Speed = Distance/Time

Calculation:

Let P and Q meet at A after t hours and V_P > V_Q

⇒ V_P - V_Q = 120 .... (1)

⇒ V_P/V_Q = 140/20 .... (2)      (When they will meet time will be the same)

⇒ V_Q = 20 km/h, V_P = 140

⇒ t = {D/(V_P + V_Q)} = (140 + 20)/(140 + 20) = 1 hours

⇒ When they meet for the second time, they together will have covered a total distance of 3D km = 3 × 160 = 480

⇒ Time required to cover the distance = 3 × 1 = 3 hours

∴ The required result will be 3 hours.