In a 500 m race, A runs at 5 m/s and B runs at 4 m/s. By how many metres does A beat B?
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → 100 m
A finishes the race in
\(500 \div 5 = 100\) seconds
In the same 100 seconds, B runs
\(4 \times 100 = 400\) m
So A beats B by \(500 - 400 = 100\) m.
Why the other options are incorrect
Option (1) 75 m — Incorrect. When A finishes, B has run 400 m, so B is 100 m behind, not 75 m.
Option (2) 80 m — Incorrect. When A finishes, B has run 400 m, so B is 100 m behind, not 80 m.
Option (4) 125 m — Incorrect. This is the distance A would run in the 25 seconds B takes extra (\(5 \times 25\)). The lead is measured by B’s shortfall when A finishes.