4. The distribution of the amount of gravel (in tons) sold by a particular construction supply company in a given week is a continuous r.v. X with pdf (x) = √11-23). (1-x²), 0 < x < 1 0, otherwise a. Find the cumulative distribution function of sales X. b. Find the expected weekly gravel sales. c. Find the median weekly gravel sales, the value of x such that F(x)=0.5.