Question

Two runners P and Q start running at 11 km/h and 13 km/h towards each other. P starts at 8 am and Q starts at 9 am. After how much time (minute) will they meet?

1.

25 min

2. 23.5 min
3. 26 min
4. 27.5 min

Answer 1

Correct Answer - Option 4 : 27.5 min

Given:

Speed of P = 11km/h

Speed of Q = 13 km/h

Starting time of P = 8 am

Starting time of Q = 9 am

Formula Used:

Speed = Distance/Time

Concept Used:

If two objects are moving with speeds S₁ and S₂ in the opposite direction

Their relative speed is S₁ + S₂

Calculation:

Distance traveled by P in 1 hour = 11 × 1 = 11 km

Distance traveled by P till 9 am = 11km

11 km is to be covered with the relative speed of both to meet.

Relative speed = 11 + 13 =24 km

Time required = 11/24 h = 11/24 × 60 min = 27.5 min

∴ They will meet after 27.5 minutes.