Hi guys, The question is from here i changed to and crossed multiplied giving me the wrong answer the right answer however is two how do we do these?

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- Jun 12th 2013, 03:30 PMGurp925Permutation question!
Hi guys, The question is from here i changed to and crossed multiplied giving me the wrong answer the right answer however is two how do we do these?

- Jun 12th 2013, 03:36 PMtopsquarkRe: Permutation question!
- Jun 12th 2013, 03:50 PMPlatoRe: Permutation question!
- Jun 12th 2013, 03:59 PMGurp925Re: Permutation question!
love Plato's method answer = 2 yay! and once we get to this portion how do we get the answer two from here ?

- Jun 12th 2013, 04:16 PMPlatoRe: Permutation question!
- Jun 12th 2013, 09:36 PMibduttRe: Permutation question!
Plato has explained very well. However we can also proceed as under

7! = 42 * ( 7-n)!

7*6* 5! = 42 * ( 7-n)!

5! = ( 7-n)!

that gives 7-n=5 OR n = 2 - Jun 13th 2013, 12:55 AMGurp925Re: Permutation question!
Great answers thanks so much guys.