A random variable y has a Rayleigh distribution, if and only if its probability distribution is given by:
f(y)=2(alpha)y^(-alpha y^2) , y>0 and alpha>0
f(y)=0 , elsewhere
a) Show that mean=(1/2)*squareroot(pie/alpha)
b) Show that the variance =(1/alpha)*(1-pie/4)