A beats B by 125 m in a kilometre race. Find B’s speed if A’s speed is 16 m/sec.
- A18 m/sec
- B14 m/sec
- C7 m/sec
- D21 m/sec
Solution & Step-by-step Explanation
In a 1 km (1000 m) race, A runs the full distance of 1000 m.
Since A beats B by 125 m, B runs:
Distance covered by B=1000−125=875 m
The time taken by A to complete the race is:
Time=
Speed of A
Distance of A
=
16
1000
=62.5 seconds
Since B covers 875 m in the same time duration (62.5 seconds):
Speed of B=
Time
Distance of B
=
62.5
875
=14 m/sec
Since A beats B by 125 m, B runs:
Distance covered by B=1000−125=875 m
The time taken by A to complete the race is:
Time=
Speed of A
Distance of A
=
16
1000
=62.5 seconds
Since B covers 875 m in the same time duration (62.5 seconds):
Speed of B=
Time
Distance of B
=
62.5
875
=14 m/sec