4. Consider the following probability density function for a continuous random variable . X: f (1) - AVI for 1 $ 1 $ 4, (a) Find the value of the parameter A so that f(x) is a valid probability deanity function. (b) Calculate E(X) and V(X). (c) Find the any" percentile for this distribution (also known as the median). (d) Find the probability that the razlom variable X is within 2 standard deviations from the mean. In other wants, find P( X - ")