Math Is Fun Forum

CroatBoy

Member

Registered: 2009-10-05

Posts: 9

Combination Word Problem

A pencil case can hold seven pens and eight pencils. Meg chooses either a pen or pencil. Then John is to choose a pen and a pencil. In which case (based on Megs initial choice) would John have to have the greater number of choices.

Does this look right?

If Meg chooses pen:

7C1x6C1x8C1
=336

If Meg chooses pencil:
8C1x7C1x7C1
=392

Therefore, John will have more choices if Meg chooses a pencil.

Last edited by CroatBoy (2009-10-05 12:30:46)

soroban

Member

Registered: 2007-03-09

Posts: 452

Re: Combination Word Problem

Hello, CroatBoy!

A pencil case can hold seven pens and eight pencils.
Meg chooses either a pen or a pencil.
Then John is to choose a pen and a pencil.
In which case (based on Megs initial choice) would John have to have the greater number of choices?

Does this look right?

If Meg chooses pen:

7C1 x 6C1 x 8C1 ?
=336

If Meg chooses pencil:
8C1x7C1x7C1 ?
=392

Therefore, John will have more choices if Meg chooses a pencil.
Right answer . . . for the wrong reasons

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