-
In a one-kilometre race, A beats B by 15 seconds and B beats C by 15 seconds. If C is 100 metres away from the finishing mark, when B has reached it, find the speed of A.
-
- 9.5 m/sec.
- 9 m/sec.
- 8 m/sec.
- 8.3 m/sec
Correct Option: D
Let B take x seconds to run 1000 m.
∴ Time taken by C
= (x + 15) seconds
| ∴ | = | = | |||
| x + 15 | 1000 | 10 |
⇒ 10x = 9x + 135
⇒ x = 135 seconds
Now in a one kilometre race, A beats B by 15 seconds.
It means A covers 1000 m in
135 – 15 = 120 seconds
| ∴ Speed of A = | = | m/sec | ||
| 120 | 3 |
= 8.3 m/sec.
