Correct Answer - Option 1 : 25/3 m/sec
Given
Total distance = 1 Km
Speed method
Let B take x seconds to run 1000 m.
∴ Time taken by C = (x + 15) seconds
Calculation
∴ \(\frac{{x}}{{x\;+\;15}}= \frac{{900}}{{1000}}= \frac{{9}}{{10}}\)
⇒ 10x = 9x + 135
⇒ x = 135 seconds
Now in a one-kilometer race, A beats B by 15 seconds.
It means A covers 1000 m in 135 - 15 = 120 seconds
∴ Speed of \(A = \frac{{1000}}{{120}} = \frac{{25}}{3}m/\sec \)