
A and B run a kilometre and A wins by 25 sec. A and C run a kilometre and A wins by 275 m. When B and C run the same distance, B wins by 30 sec. The time taken by A to run a kilometre is

 2 min 25 sec
 2 min 50 sec
 3 min 20 sec
 3 min 30 sec
Correct Option: A
If A covers the distance of 1 km in x seconds, B covers the distance of 1 km in (x + 25) seconds. If A covers the distance of 1 km, then in the same time C covers only 725 metres.
If B covers 1 km in (x + 25) seconds, then C covers 1 km in (x + 55) seconds.
Thus in x seconds, C covers the distance of 725 m.
∴  × 1000 = x + 55  
725 
⇒ x = 145
∴ A covers the distance of 1 km in 2 minutes 25 seconds.