In a 400-metre race, A runs at a speed of 16 m/sec. If A gives B a start of 15 meters and still beats him by 10 sec, then what is the speed of B?
Show answer & explanation
Correct answer: A
Explanation
The correct answer is Option 1. i.e. 11 m/sec.
Total distance = 400 m
Speed of A = 16 m/s
Diatance = Speed × Time
A covers the total distance in 400/16 = 25 seconds
Now, according to the question, B has given a start of 15 m
⇒Then, distance covered by B = 400 - 15 = 385 m
⇒Time taken by B to cover this distance = 25 + 10 = 35 seconds (given)
⇒So, speed of B = 385/35 = 11 m/s
Hence the speed of B is 11 m/s.