Question

A and b take part in 100 m race. a runs at 5 kmph. a gives ba start of 8m and still beats him by 8 seconds. the speed of b is:

Answer 1

1km=1000metres

1hour=60minutes=60*60=3600seconds

speed of A is 5000metres per 60minutes(3600seconds)

A runs 5000 metres in 3600seconds

therefore A ran 100 metres in 3600/5000*100=72seconds

As A gave 8 metre headstart to B, therefore B actually covered 92 metres .

A ran 100 metres in 72seconds which was 8 seconds faster than B

Therefore B ran 92 metres in (72+8)=80seconds

In 80seconds B covers 92 metres

Therefore in 3600seconds(1 hour) B covers 4140metres

The speed of B is 4.14 kmph