Query about question from probablity "Given an uniformly-distributed random variable..." [5902]

https://www.gregmat.com/problems/quant?problem=given-an-uniform-random-variable


I am not able to understand the solution to this GRE problem. Can someone please explain how to approach this problem from uniform random variable?

You can ignore it because it is an extreme question.

However, you can check The new "extreme" quant question out if you insist on solving it.