ASM Quiz 57-1

Hello. I am using the most recent edition of the ASM manual to study. Can someone please help me with quiz 57-1 - in particular the derivation of V_a and V_b ?

What I thought to do for V_a was calculate the following :
E(A)=0*0.75 + 1*0.25 = 0.25
E(A^2)=0^2*0.75 and 1^2*0.25=0.25
And then solve for V_a like
V_a = 0.25 - 0.25^2 = 0.1875

I used a similar methodology for V_b

To get v I just took:

v=0.5(V_a + V_b) which is done in the solution, however they have different values of V_A and V_b

Can someone please help ?

Please let me know if this isn't clear enough and I'll try to elaborate more!

Thanks in advance!


ASM Quiz 57-1