Skip to main contentSkip to solution

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?

Solution

✅ Correct Option: 4

A runs 9 times slower than B. When B runs 9 meters, A runs 1 meter.

Speed ratio B : A = 9 : 1

Let A's speed = 1x1x and B's speed = 9x9x


B gives A a start of 80 meters means A starts 80 meters ahead of B.

Let the winning post be at distance dd meters from the starting line.

B has to run: dd meters

A has to run: (d−80)(d - 80) meters


Since they reach at the same time:

Time for A = Time for B

d−801x=d9x\frac{d - 80}{1x} = \frac{d}{9x}

d−80x=d9x\frac{d - 80}{x} = \frac{d}{9x}

d−80=d9d - 80 = \frac{d}{9}

9(d−80)=d9(d - 80) = d

9d−720=d9d - 720 = d

8d=7208d = 720

d=90d = 90


The winning post must be 90 meters from the starting line.

Keyboard Shortcuts

  • Left arrow: Previous question
  • Right arrow: Next question
  • S key: Jump to solution
  • Q key: Jump to question