Letx1andx2be a random sample of observations from a population with meanand variance 2. Consider the following point estimators, W, X, Y, and Z of:W = (x1+x2)/2; X = (2x1+x2)/3; Y = (x1+ 3x2)/4; and Z = (2x1+ 3x2)/5.

What is the relative efficiency of Z with respect to Y?

a.

1.20

b.

0.80

c.

1.50

d.

0.50