Picking Marbles from a bag--Probability

Could anyone help me out?

There are 100 marbles in a bag, 50 blue, 40 red, and 10 purple. You draw three times returning a marble to the bag each time you draw (this makes one game). What is the probability of getting 1 purple, 1blue, and 1 red? Purple, then blue, then purple? Red, then blue, then red?

I found out that there are 27 total possibilities, so would it just be # of times that it comes up/27 or would the probability of picking each marble play into this also?