[chels_kep]

An urn contains 4 red, 4 white, and 4 blue marbles. In how many ways can 3 red and 2 blue marble(s) be selected?

[Unknown008]

I'm assuming that the total number of marbles to be picked is 5 and that you are looking for the probability that you pick 3 red and 2 blue marbles.

The number of ways to pick the 3 red and 2 blue marbles can be found as follows:

There are 5 marbles, of which 3 are red and 2 blue.

Hence you have: number of ways of getting 3 red and 2 blue marbles.

I think you can now proceed with the probability.