Three different numbers are randomly selected from among the first ten positive integers. Find the probability that the sum of these three numbers is 15.
+97 There are a total of 10*9*8 or 720. Lets see what 3 numbers sum up to 15.
We have the following:
1 6 8 gives us 6 ways.
1 5 9 gives us 6 ways.
1 4 10 gives us 6 ways.
2 6 7 gives us 6 ways.
2 5 8 gives us 6 ways.
2 4 9 gives us 6 ways.
2 3 10 gives us 6 ways.
3 4 8 gives us 6 ways.
3 5 7 gives us 6 ways.
4 5 6 gives us 6 ways.
Adding up the possible ways we get 60 ways.
60/720 is 1/12.
