Sunday, 21 July 2013

If you roll two fair six-sided dice, what is the probability that the sum is 4 or higher?





If you roll two fair six-sided dice, what is the probability that the sum is 4 or higher?




The answer is 3336 or 1112. I understand how to arrive at this answer. What I don't understand is why the answer isn't 911? When summing the results after rolling two fair six sided dice, there are 11 equally possible outcomes: 2 through 12. Two of these outcomes are below four, meaning 9 are greater than or equal to four which is how I arrived at 911. Can someone help explain why that is wrong?


Answer



It is wrong because it is not 11 equally possible outcome.



There is exactly 1 way to get the sum to be 2. (1+1=2)



but there is more than one way to get 3. (1+2=3,2+1=3)



No comments:

Post a Comment

real analysis - How to find limhrightarrow0fracsin(ha)h

How to find lim without lhopital rule? I know when I use lhopital I easy get $$ \lim_{h\rightarrow 0}...