- #1

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I'm having a hard time figuring out why it is 7 Chooses 4?

thx

- Thread starter Bachelier
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- #1

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I'm having a hard time figuring out why it is 7 Chooses 4?

thx

- #2

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you see, in the context of this problem , why 7C4=7C3?

- #3

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Yes, because we for 3 zeros and 4 ones.Can

you see, in the context of this problem , why 7C4=7C3?

- #4

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Exactly. Perfect. This is the general identity nCk =nC(n-k).

- #5

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Thank you :)Exactly. Perfect. This is the general identity nCk =nC(n-k).

- #6

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No problem; glad to help.

- #7

chiro

Science Advisor

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If you want to get some intuition, what you can do is to start with 1111000, and then find every way of re-arranging these digits so that each rearrangement is different from each other. For example 1111000 goes to 1110100, 1110010, 1110001 and so on.

I'm having a hard time figuring out why it is 7 Chooses 4?

thx

Using this as your intuition base, you can develop a factorial relationship which will eventually give you the "N choose R" formula that you use.

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