When body slides down from rest along smooth inclined plane making angle of `45^(@)` with

When body slides down from rest along smooth inclined plane making angle of `45^(@)` with the horizontal, it takes time `T` When the same body slides down from rest along a rough inclined plane making the same angle and through the same distance it is seen to take time `pT`, where p is some number greater that 1. Calculate late the coefficient of friction beween the body and the rough plane. .