If you roll 2 die, what is the probability that you will get a sum of 11? What about a sum of 5?

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Answer 1 · 2015-11-18T11:37:40

The probabilities are: #P(A)=1/18#; #P(B)=1/9#.

To calculate the probabilities we have to calculate the number of all elementary events first.

#bar(bar(Omega))=6^2=36#

Event #A#-"sum of numbers is 11" consist of 2 elements:

#A={(6,5);(5,6)}#,

so #P(A)=2/36=1/18#

Event #B#-"a sum of numbers is 5" consist of 4 elements:

#B={(1,4);(2,3);(3,2);(4,1)}#

so #P(B)=4/36=1/9#