Expand the parentheses as far as possible for the following expressions

(a) E(ax+by)forx,yvariablesanda,bscalars

(b) E(axy) for x,y independent variables and a a scalar

(c) E(axy) for x,y correlated variables and a a scalar

(a) Explain the difference between a pdf and a cdf

(b) What shapes are the pdf and cdf for a normally distributed random

variable?