Question

The distance between two cities P and Q is 220 km. Car A starts travelling from P at 40 km/h at 8.00 am towards Q and simultaneously Car B travels from Q at 60 km/h at 10.00 am towards P. Find the ratio of distance travelled by A and B, when they met.
1. 21 ∶ 32
2. 17 ∶ 21
3. 21 ∶ 34
4. None of these

Answer 1

Correct Answer - Option 4 : None of these

Given:

Total Distance = 220 km

Speed of A = 40 km/h

Speed of B = 60 km/h

Formula Used:

Time = Distance/Speed

Concept Used:

Relative Speed = Speed of one object with respect to other object

When two object of Speed V₁ and V₂, respectively travels in opposite direction the the relative Speed = |V₁ + V₂|

Calculations:

Car A starts at 8.00 am, Distance travelled by A at 10.00 am = 40 × 2 = 80 km

Car B starts from Q at 10.00 am

So, Relative speed = 60 + 40 = 100 km/h

Distance between A and B at 10.00 am = 220 – 80 = 140 km

Time taken to meet, 140/100 = 1.4 h

Total time taken by A = 2 + 1.4 = 3.4 h

Total distance travelled by A in 3.4 h = 40 × 3.4 = 136 km

Total time taken by B = 1.4 h

Total distance travelled by B = 60 × 1.4 = 84 km

Required ratio = 136 ∶ 84 = 34 ∶ 21

∴ The ratio of distance travelled by A and B, when they met is 34 ∶ 21