Question

A thief,after commuting a theft runs at a uniform speed of 50m/min.After 2minutes a policeman runs to catch him.He goes 60m in first minute and increases his speed by 5m/min every succeeding minute.After how many minutes,the policeman will catch the thief?

Answer 1

In first two minutes thief already coverd =50x2=100m
So first policeman have to cover it but at the same time thief is also running
So total relative speed in first minute =60-50=10m in 1 min
In next 1 min 65-50=15m in next 1 min
Similarly
70-50=20 in next 1min
75-50=25 in next 1 min
80-50=30 in next 1 min
10+15+20+25+30=100m
So policeman catch him in next 5 minutes

Answer 2

this is the complete answer...