Originally Posted by

**rikari** Hi,

I'm thinking if you can help me think of a better way to solve this.

Here's the situation

I have probabilities of the number of bags I can sell in a day

2 - 30 %

3 - 28%

4 - 20%

5 - 16%

6 - 6%

Now, I want to know the probability of selling, for example, 8 bags after 3 days.

What I did so far is this,

I get all the permutations of 3 numbers out of {2, 3, 4, 5, 6}, where the sum is 8, so I have the following with their respective probabilities

2,2,4 = .30*.30*.20 = .018

2,3,3 = .30*.28*.28 = .02352

2,4,2 = .30*.20*.30 = .018

3,2,3 = .28*.30*.28 = .02352

3,3,2 = .28*.28*.30 = .02352

4,2,2 = .20*.30*.30 = .018

thus, the probability of selling 8 bags after 3 days is .018+.02352+.018+.02352+.02352+.018 = .12456

My problem is, I need to get all the possible number of bags sold in 3 days with their probabilities of occurring. Is there a way that I can compute for that easily? The true situation is working with more than 5 possible number of bags in a day.