1) let x be a random variable having expected value M and
variance o^2. find the expected value and vartmce of y= x-m/o^-

ii) give the moment g . f mx(1)=e^3t+8t2 , find the m . g . f
function ot the random variable -2=1/4(x-3) and use it to determine
the mean and the variance of z.

iii) if x1 , x2 and x5 are independetand have mean 4,9 and 3
with variances 3, 7and 5, find the coriarance of x,y coc (x,y)