[mykey1961]

[ QUOTE ]
Your simplification of the EV equation is incorrect.

Here it is step-by-step, so you can point out specific errors if you disagree:

(3-3x)/2 (1.5x + 3.5 * 1/3 * (1-x) - 2.5 * 2/3 * (1-x))
...
(3-3x)/2 (4.5x/3 + 3.5/3 - 3.5x/3 - 5/3 + 5x/3)
...
(3-3x)/2 * (4.5x + 3.5 - 3.5x - 5 + 5x)/3
...
(1-x)/2 * 6x - 1.5
...
(6x - 6x^2 - 1.5 + 1.5x)/2
...
(-6x^2 + 7.5x - 1.5)/2
...
-3x^2 + 3.75x - .75

The derivative is:
-6x + 3.75
so
6x = 3.75
x = 3.75/6 = 0.625

x = 0.625, a = 0.4375


[/ QUOTE ]

why a = 0.4375

the EV(sb) is the same for a >= 0.0, a <= 0.625
the EV(sb) is worse for a > 0.625