Problem 192 Solution

Assume the matrix looks like this.
Problem 192
Player A Player B
Rock Paper
Rock a b
Paper c d

First, verify neither player is always better off with one strategy. If a>c and b>d then player A will always choose rock. Likewise, if a>b and c>d, the player B will always choose paper. Assuming there is no obvious pick for either player then it becomes a random strategy.

Player A should pick rock with a probability propotional to abs(c-d), and paper with probability proportional to abs(a-b).

Player B should pick rock with a probability propotional to abs(b-d), and paper with probability proportional to abs(a-c).

Here, again is the matrix for this problem.

Problem 192
Player A Player B
Rock Paper
Rock 7 3
Paper 2 11

Player A should pick rock with probability abs(2-11)/(abs(2-11)+abs(7-3)) = 9/(9+4) = 9/13.

Player A should pick paper with probability abs(7-3)/(abs(2-11)+abs(7-3)) = 9/(9+4) = 4/13.

Player B should pick rock with probability abs(3-11)/(abs(3-11)+abs(7-2)) = 8/(8+5) = 8/13.

Player B should pick paper with probability abs(7-2)/(abs(3-11)+abs(7-2)) = 5/(8+5) = 5/13.

Player A's average win will be (9/13)×(8/13)×7 + (9/13)×(5/13)×3 + (4/13)×(8/13)×2 + (4/13)×(5/13)×11 = 2.982248521 + 0.798816568 + 0.378698225 + 1.301775148 = 5.461538462

For help with this problem I recommend 'The Complete Strategyst' by J.D. Williams.

Michael Shackleford, A.S.A.