In a 400-metre race, A runs at a speed of 16 m/sec. If A gives B a start of 15 metres and still beats him by 10 sec, then what is the speed of B?

Correct option is A

Given:

Speed of A = 16 m/sec

Start given to B = 15 metres

A beats B by 10 seconds

Total distance of the race = 400 metres

Concept Used:

Time = Distance / Speed.
The effective distance covered by A and B is the same, but A takes 10 seconds less to complete the race.
Using the relationship between time, distance, and speed, we can calculate the speed of B.

Solution:

Time taken by A to complete the race:

Time = Distance / Speed = 400 / 16 = 25 seconds

Time taken by B to complete the race:

Time = 25 + 10 = 35 seconds

Effective distance covered by B:

Distance = Total distance - Start given = 400 - 15 = 385 metres

Speed of B:

Speed = Distance / Time = 385 / 35 = 11 m/sec