A box contains exactly five chips, three red and two white. Chips are randomly removed one at a time without replacement until all the red chips are drawn or all the white chips are drawn. What is the probability that the last chip drawn is white?
So I found the answer. It says,
Let's assume we don't stop picking until all of the chips are picked. To satisfy this condition, we have to arrange the letters: W, W, R, R, R such that both W's appear in the first 4. We find the number of ways to arrange the white chips in the first 4 and divide that by the total ways to choose all the chips. The probability of this occurring is 4C2/5C2 = 3/5