In a 1000 m race. A beats B by 50 meters or 15 seconds. The time taken by A to complete the race is :

285 seconds

The correct answer is Option (3) → 285 seconds

Let the speed of A and B be x, y respectively.

$y=\frac{950}{T}=\frac{1000}{T+15}$

$⇒950(T+15)=1000T$

$⇒50T=14250$

$⇒T=\frac{14250}{50}=285$

A takes 285 seconds to complete the race.