Question

A thief drives at the speed of x km/hr. The policemen started chasing him after 4 hours and catches him in 4 hours. Find the speed of the thief if the speed of the policemen is 40 km/hr?

Answer 1

Answer:

then travels the next 160 km at the speed of 80 km/hr. What is the average speed for the first 320 km. 10). A thief running at speed of 8 km/hour is chased by a policeman at a speed of 10 km/hour.

Answer 2

The speed of the thief is 20 km/h .

Given :

Let , speed of thief is x km/hr .

Also , policemen started chasing him after 4 hours and catches him in 4 hours.

Distance , travelled by the thief in 4 + 4 hours is :

$d = 8x\ km$ .

Also , distance , covered by the police in 4 hours is :

$D=40\times 4=160\ km$ .

To catch the thief distance covered by the thief is equal to distance covered by the police .

Therefore ,

d = D

$8x=160\\x=20\ km/h$

Hence , this is the required solution .

Learn More :

Kinematics

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