Hey guys, here is my question:
Greg rolls 3 six-sided dice. Find the probability that the sum of the 3 dice is less than 9.
I realize that one possible way to go about this, would be to list all the cases in which the sum is less than 9, then divide by the total number of cases, but this seems too time consuming. Does anyone know of a more efficient way to go about this problem?
Here is a web-tool to help with this question.
Look at the coefficients of the x’s.
The coefficient of is 1. There is one way to roll 3.
The coefficient of is 21. There are twenty-one ways to roll 8.
If you change the 3 to 4 on the whole sum, you get the ways to roll four dice.