5 people go to a movie theathre. They consign their hats to a cloakroom. What is the probability that when they leaved the theathre 2 of them got their hats?

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- March 21st 2014, 12:34 PM #1

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- March 21st 2014, 12:52 PM #2
## Re: hat problem

Read the article.

your answer is {5 choose 2}*{derangement of three}

- March 21st 2014, 01:35 PM #3

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## Re: hat problem

Hello, kastamonu!

Five people go to a movie theatre and consign their hats to a cloakroom.

What is the probability that when they leave the theatre, exactly 2 of them got their hats?

Assuming that the hats are returned randomly,

. . there are possible outcomes.

Call the people

First, choose the two people who get their hats.

. . There are: . choices.

Suppose they are and

Then do not get their hats.

There are 2 choices: . and

Hence, there are: . ways.

The probability is: .

- March 22nd 2014, 01:23 AM #4

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