# Need some help determining if there is more I have to do with this question

• Dec 2nd 2011, 12:24 PM
Need some help determining if there is more I have to do with this question
"A bag contains 3 red balls, 4 yellow balls, and 5 white balls. If two balls are being drawn from the bag without replacement, what is the probability that the first ball is yellow and the second ball is white?"

So I know that to calculate the probability of drawing two balls you calculate the individual probability of drawing each ball then multiply them together. But do I need to do any additional calculations for the probability that they are drawn in the correct order (first is red, second is white)? If so, what equation would I use to do that? Or am I over-thinking this?
• Dec 2nd 2011, 12:29 PM
Plato
Re: Need some help determining if there is more I have to do with this question
Quote:

Originally Posted by DEADTERMINATOR
"A bag contains 3 red balls, 4 yellow balls, and 5 white balls. If two balls are being drawn from the bag without replacement, what is the probability that the first ball is yellow and the second ball is white?"

The answer is $\frac{?}{?}\cdot\frac{5}{11}$.
Now you fill in ??
• Dec 2nd 2011, 12:32 PM
HallsofIvy
Re: Need some help determining if there is more I have to do with this question
No, that's all you need to do. Initially there are 3 red balls, 4 yellow balls, and 5 white balls for a total of 12 balls. The probability of drawing a yellow ball is 4/12= 1/3. Once that is done, there are 3 red balls, 3 yellow balls, and 5 balls for a total of 11 balls. The probability of drawing a white ball is 5/11. Yes, multiply them together.