x is an exponential random variable with a mean of 5 and y is a rayleigh variable of second moment .obtain the following (a) var(2x-3) (b) e(exp(-3x) ) , (c) e(2y2 5) and (d) var(4-y) .

a) Var(2X - 3) = 4σ², where σ is the standard deviation of X.
b) Var(2X - 3) = 5, where 5 is the mean of X.
c) Var(2X - 3) = 8, where 8 is twice the mean of X.
d) Var(2X - 3) = 2σ², where σ is the standard deviation of X