We were given the following joint probabiltiy density function for the random variables Y1 and Y2, which were the proportions of two components in a sample from a mixture of insecticide:

f(y1,y2)={2, 0<=y1<=1, 0<=y2<=1, 0<=y1+y2<=1. 0, elsewhere}

For the two chemicals under consideration, an important quantity is the total proportion Y1+Y2 found in any sample. Find E(Y1+Y2) and V(Y1+Y2).