Question

Police started chasing a thief at 6 am while the theft was reported at 4 am. If the speed of police and thief was 77 km/h and 55 km/h respectively, find at what time the police caught the thief.

1. 11 am 
2. 10 am 
3. 8 am 
4. 9 am

Answer 1

Correct Answer - Option 1 : 11 am 

Given:

Speed of policeman = 77 km/h

Speed of thief = 55 km/h

Time of reporting = 4 am

Time at which police started chasing = 6 am

Formula Used:

Speed = Distance/Time

Concept Used:

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

Their relative speed is S₁ – S₂

Calculation:

There was a gap of 2 hours

Distance traveled by the thief in 2 hours = 55 × 2 = 110 km

Now, the police started chasing

Relative speed = 77 – 55 = 22 km/h

Time = 110/22 = 5 h

∴ Police caught the thief at 11 am.