Permutation and combination -Finding n

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Source: — Problem Solving |

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by Brent@GMATPrepNow » Sun May 04, 2014 5:11 am
s91arvindh wrote:A person can invite one or more of his friends for lunch in a maximum of 500 ways. The number of friends he has may be
a) 4 b) 6 c) 8 d) 10
[spoiler]
Answers are a,b,c[/spoiler]

Note: The questions are from handouts provided
This question is poorly worded. Also, Problem Solving questions on the GMAT do not have 3 correct answers. Also, Problem Solving questions always have FIVE answer choices.

If a person has n friends, he can invite one or more of those friends to lunch in (2^n) - 1 ways.

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Brent
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by s91arvindh » Sun May 04, 2014 5:31 am
Thanks Brent !

These questions are given for in depth understanding the concept of permutation and combination.