The ratio of speed of A and B is 4 : 7 and A loses the race by 270 m, then find the length of the race.

630 m

The time is same for A and B. 

Therefore, Distance ∝ Speed,

                  A          :           B

Speed         4          :           7

Distance      4          :           7          Difference = 3R

3R = 270

1R = 90

The length of race = distance covered by B = 7 × 90 = 630 m