The length of time, in minutes, for and airplane to obtain clearance for take off at a certain airport is a random variable Y=3X-2, where x has the density function
f(x) = { 1/4e^(-x/4), x>0
0, elsewhere,
Find the mean and variance of the random variable Y.
the answer from the text book are: mean of Y = 10, variance = 144;
anyone know how to get the answers?