Answer & Solution
B : C = 1000 : 850
$$\eqalign{ & \therefore \frac{A}{C} = \frac{A}{B} \times \frac{B}{C} \cr & \,\,\,\,\,\,\,\, = \frac{{1000}}{{900}} \times \frac{{1000}}{{850}} \cr & \,\,\,\,\,\,\,\, = \frac{{1000}}{{765}} \cr} $$
A : C = 1000 : 765
∴ A beats C by (1000 - 765) m = 235 m