CBSE Class 10 Answered

In 1 min distance covered by thief = 100 x 1 = 100 m

Therefore gap between thief and police = 100 m

When police starts chasing, his speed in 1st min is same as that of thief.

Therefore ther is no change in the gap.

In the 2nd min of chase, speed difference is 10.

Therefore the gap also reduces by 10 m.

Similarly the gap reduces by 20 m in 3rd min.

Now 0 + 10 + 20 + 30 + 40 = 100

Therefore it takes 5 mins for police after he starts to catch the thief.

Therefore policeman takes total of 6 min after the thief starts running.