SOLUTION: I'm getting dressed in the dark, and I have 9 pairs of white socks and 9 pairs of black socks, but they're all mixed up in my sock drawer. How many socks will I need to blindly pu

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Question 1200664: I'm getting dressed in the dark, and I have 9 pairs of white socks and 9 pairs of black socks, but they're all mixed up in my sock drawer. How many socks will I need to blindly pull out to ensure that I get five pairs of white socks?
Found 2 solutions by Edwin McCravy, ikleyn:
Answer by Edwin McCravy(20063)   (Show Source): You can put this solution on YOUR website!
There are 18 white socks and 18 black socks, and you want 10 white socks. The
worst possible case is that you draw all 18 black socks before you have drawn 10
white socks. So you would have to draw 18+10=28 socks to be sure you have 10
white socks.

Edwin
Answer by ikleyn(52872)   (Show Source): You can put this solution on YOUR website!
.

From the context, the socks are disjoint.


In the worst case, you will take in the dark 9 pairs = 9*2 = 18 black socks,
without knowing what color they are.

Add to it  5*2 = 10  other socks from the box,  and you will be guaranteed of having  5  pairs of white socks.

So,   18 + 10 = 28 socks   is your answer in this problem.

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To see many other similar  (and different)  solved problems,  look into the lesson
    - In the worst case
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