A Pair Of Dice Are Rolled And The Sum On Their Upturned Faces Is Recorded. What Is The Probability That The Sum Showing Is 8, Given That One Die Is Showing A 5?


2 Answers

Pete (the Idiot) Profile
The only way the sum is 8 with one showing 5 is for the other one to show 3.
Each total has 1 in 12 chances to appear, so the probability is 1:12, 1/12th, or 8.33%

thanked the writer.
Stewart Pinkerton
Actually no, one die is defined as showing 5, so the probability of the other being 3 is 1/6, or 16.67%
Oddman commented
Actually, no. There are 11 ways that one die can show a 5. Of these, 2 result in a sum of 8. The probability of 8 given that one die shows 5 is 2/11 ≈ 18.2%
Pete (the Idiot)
Pete (the Idiot) commented
Unbelievable. Not only providing the wrong answer but also giving me a thumbs down. Grow up already.
Anonymous Profile
Anonymous answered
One of the dice is accounted for because it is showing a 5. This takes that entire die out of the equation because six of twelve possible sides are now accounted for. This leaves us with a single six sided die of which the number we need is a 3. One out of six sides is a three so the answer is 1 in 6.

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