26. A Seattle newspaper intends to administer two different surveys relating to two different anti-tax initiatives on the ballot in November. The proportion of surveys mailed that will actually be completed and returned to the newspaper can be represented as the outcome of a bivariate random variable (X, Y) having the density function 2

I(x,y) = a(x + 2y)I[o,lI(x)I[o,II(Y), where x is the proportion of surveys relating to initiative I that are returned, and y refers to the proportion of surveys relating to initiative II that are returned.