It's obvious that half the possible rolls will have an odd sum

and the other half will have an even sum.  So the probability

is obviously .  Or another way to explain it is:



The rolls colored red below have an odd sum and so the probability

of rolling one of the red rolls is 18 out of the 36 possible rolls 

which is  which reduces to :



⚀⚀   ⚀⚁   ⚀⚂   ⚀⚃   ⚀⚄  ⚀⚅



⚁⚀   ⚁⚁   ⚁⚂   ⚁⚃   ⚁⚄  ⚁⚅



⚂⚀   ⚂⚁   ⚂⚂   ⚂⚃   ⚂⚄  ⚂⚅



⚃⚀   ⚃⚁   ⚃⚂   ⚃⚃   ⚃⚄  ⚃⚅



⚄⚀   ⚄⚁   ⚄⚂   ⚄⚃   ⚄⚄  ⚄⚅



⚅⚀   ⚅⚁   ⚅⚂   ⚅⚃   ⚅⚄  ⚅⚅



Edwin 

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