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topspin360
- Master | Next Rank: 500 Posts
- Posts: 103
- Joined: Sat Jun 02, 2012 9:46 pm
- Thanked: 1 times
Hello,
I understand how to do the original question but can you please explain how to solve my version of the question (posted underneath the question below).
If there are 30 red and blue marbles in a jar, and the ratio of red to blue marbles is 2:3, what is the probability that, drawing twice, you will select two red marbles if you return the marbles after each draw? -understand how to do this.
***What if the question said: draw 3 times, replacing marbles each time. What is the probability of getting red marbles exactly twice? At least twice?
I know I can't use the counting principal alone (12/30 * 12/30 * 18/30). How do i do it? Can i use combinatorics on the counting principal? so it would be: 3! * (12/30 * 12/30 * 18/30)?
Thanks.
I understand how to do the original question but can you please explain how to solve my version of the question (posted underneath the question below).
If there are 30 red and blue marbles in a jar, and the ratio of red to blue marbles is 2:3, what is the probability that, drawing twice, you will select two red marbles if you return the marbles after each draw? -understand how to do this.
***What if the question said: draw 3 times, replacing marbles each time. What is the probability of getting red marbles exactly twice? At least twice?
I know I can't use the counting principal alone (12/30 * 12/30 * 18/30). How do i do it? Can i use combinatorics on the counting principal? so it would be: 3! * (12/30 * 12/30 * 18/30)?
Thanks.
