Consider the following functions of the random variables Y1, Y2, Y3: W1 = Y1 + Y2 + Y3 W2 = Y1 − Y2 W3 = Y1 − Y2 − Y3 1. (5 points) State the above in matrix notation. I. e., express the vector W = [W1, W2, W3] T as the product of a matrix and the vector Y = [Y1, Y2, Y3] T . 2. (5 points) Express the expectation of the random vector W in terms of the expectations of the Yi ’s. 3. (10 points) Express the variance-covariance matrix of W in terms of the variances and covariances of the Yi ’s (i. e., compute the elements of the Cov(W) matrix).