The ratio of speed of A and B is 7 : 10 and A loses the race by 210 m, then find the length of the race.

720 m 670 m 630 m 700 m

700 m

The time is same for A and B.  Therefore, Distance ∝ Speed,                   A          :           B Speed         7          :           10 Distance      7          :           10          Difference = 3R 3R = 210 1R = 70 The length of race = distance covered by B = 10 × 70 = 700 m