A distribution center for a chain of electronics stores receives orders from the various branches. When an order is received, an amount of time, X, is required to collect the items ordered by the store, and then an amount of time, Y , is required to load all the items onto a delivery truck. The characteristics of the two random variables are as follows: E(X) = 1.5 hours, SD(X) = 0.4 hours; E(Y )=2.2 hours, SD(Y ) = 0.5 hours. The correlation between X and Yis=0.95.

About the time required to fill an order (that is, the time required to have the delivery truck loaded and ready to go) once an order is received at the distribution center, please calculate

(a)E(X+Y)

(b)Cov(X, Y)

(c)Var(X+Y)

(d)SD(X+Y)