Distance after 10 seconds

A body falls from rest so that its distance from the starting point varies as the square of the time. If it falls $402\frac{1}{2}$ feet in 5 seconds, how far does it fall in 10 seconds?

H. S. Hall & S. R. Knight, Higher Algebra (1891) · Ch. III. Variation, Examples III, No. 15 (part 1)