Brother: U& Twfx too smart ,I do it by tipical math.

Let 20=1,60=3. 3 periods.[0,1],[1,2] and [2,3]
[0,1]:
p(x)=(1+x)/3. Intg(1+x)/3 from 0 to 1,It is 1/2
[1,2]:
p(x)=2/3 ....it is 2/3
[2,3]:
p(x)=(2-x)/3.........it is 1/2.
1/3(1/2+2/3+1/2)=5/9.
Sorry ,I'm too old to do by heart.

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• good! different ways to the same destination. -皆兄弟也- ♂ (0 bytes) () 04/16/2010 postreply 08:28:42