The joint probability distribution of the random variables is f(x,y)= 8xy, 0<=y<=x<=1. fine the covarience of x and y

Porphyrin is a pigment in blood and other body fluids that is significant in body energy and storage.  Let x be a random variable that represents the number of milligrams of porphyrin per deciliter of blood.  In healthy adults x is approximately normally distributed with μ = 38 and σ = 12.  What is the probability that x is less than 60?

Find the first two moments about the mean for the random variable X defined by X = -2 with prob. 1/3 3 with prob. 1/2 = 1 with prob. 1/6. %3D

The random variable X has a distribution function:F(x) = 0 ; x < 3       = 1/c(x2 - 3x) ; 3 <= x <=6       =  1 ; x > 6 Count the value of constant "c" Count the P(X > 4) and P(5 <= X <= 6) Count the median of X Thanks for help!