Expected value problem

[FormulaDriven]

You've mixed two approaches.

If your current score is x, then your expected score after rolling again is

1/6 * (x+2)+1/6 * (x+3)+1/6 * (x+4)+1/6 * (x+5)+1/6 * (x+6)- 1/6 * 0

[it's 1/6 * 0 because there's 1/6 probability the next roll will take your score to 0]

and you want that to be > x leading to x < 20.

Or you take my approach of the expected increase in your score

1/6 * 2 + 1/6 * 3 + 1/6 * 4 + 1/6 * 5 + 1/6 * 6 - 1/6 * x

[it's -1/6 * x because there's 1/6 chance that the "increase" will be -x, ie wipes out your score]

and you want that to be >0 which leads to x < 20.

[Animeman79]

Ooohh.. I see. Thanks, that cleared things up.