In a kilometre race, A beats B by 30 seconds and B beats C by 15 seconds. If A beats C by 180 m, the time taken by A to run 1 kilometre, is ?

Answer: Option B

In a km race, suppose A takes t sec,
Then, B takes (t + 30) sec, and C takes (t + 45) sec
180 m is covered by C in 45 sec
∴ 1000 m is covered by C in
= $$\left(\frac{45}{180}\times 1000\right)$$   sec
= 250 sec
∴ A covers 1000 m in
= (250 - 45) sec
= 205 sec