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Mathematics 13 Online
OpenStudy (anonymous):

how many 3 person committees are possible from a group of 10 people if either jim or mary but not both must be on the committee

hero (hero):

Okay, I've figured it out

hero (hero):

1. Create two separate groups. Put Jim, Mary in the first group. Put the remaining eight people in the other group: Group one: Jim, Mary Group two: The other eight committee members 2. Choose one person from the first group, then choose 2 people from the second group. 2C1 * 8C2

OpenStudy (anonymous):

so the answer is 16?

hero (hero):

It's not 16. I don't know how you got that bro. Do you not know how to calculate combinations?

hero (hero):

Use the combinations formula and multiply both combinations together.

hero (hero):

I practically gave you the answer and you still don't know how to calculate it.

hero (hero):

Did you figure it out yet bro?

hero (hero):

You use the combinations formula \[nCr = \frac{n!}{r!(n-r)!}\]

OpenStudy (anonymous):

i got 36

hero (hero):

It's not 36

hero (hero):

How are you calculating these bro?

OpenStudy (anonymous):

8!/2!6! 8*9/2*1=36

hero (hero):

You only calculated one of them

hero (hero):

And I don't believe it's right

OpenStudy (anonymous):

did u get 28

hero (hero):

8C2 = 28 Yes, but what about 2C1

hero (hero):

That's also a part of the calculation.

hero (hero):

You're supposed to calculate 2C1 x 8C2

OpenStudy (anonymous):

64?

hero (hero):

That's still not correct.

hero (hero):

Are you using the formula I gave you?

hero (hero):

Communicate with me faster.

OpenStudy (anonymous):

ya i used it for 28 but how do i get the other number

hero (hero):

You use the same formula

OpenStudy (anonymous):

okay so it would be 28 times 2

hero (hero):

Yes, which equals what?

OpenStudy (anonymous):

56

hero (hero):

56 is the correct answer....finally.

OpenStudy (anonymous):

thank you so muich for your time and patience i appreciate it!

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