A runs 9 times slower than B. If B gives A a start of 80 meters, how far must be the wining post on the tracks so that A and B reach there at the same time?
Answer & explanation
Correct answer: option 4
The correct answer is Option (4) → 90 meters
Let the speed of A be $v$. Then speed of B = $9v$ (since A runs 9 times slower).
A is given a start of 80 m, so distance for A to reach the post = $D - 80$, and distance for B = $D$.
Time taken by both to reach the post must be equal:
$\frac{D-80}{v} = \frac{D}{9v}$
Multiply both sides by $9v$:
$9(D-80) = D$
$9D - 720 = D$
$8D = 720$
$D = 90$
Winning post distance = 90 m