Let X, Y, Z and be independent Gaussian random variables with equal means of µ =3 and variances 
Estimate the mean and variance of 
constructing a large number of realizations of this random variable in MATLAB and then computing the sample mean and sample variance.
How many samples of the random variable were needed before the sample mean and sample variance seemed to converge to a fairly accurate estimate. (To answer this, you must define what you mean by "fairly accurate.")