SOLUTION: in how many ways can one invite one or more of five friends to her a party?

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Question 1119364: in how many ways can one invite one or more of five friends to her a party?
Found 2 solutions by ikleyn, Alan3354:
Answer by ikleyn(52780) About Me  (Show Source):
You can put this solution on YOUR website!
.
The number under the question = the number of all non-empty sub-sets of the set of 5 elements.


Answer.  In 2%5E5+-+1 = 32-1 = 31 way.

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The solution uses well known fact that the total number of subsets of a given set of N elements is 2%5EN, including the empty subset and improper subset.

See the lesson
    - How many subsets are there in a given finite set of n elements?
in this site.



Answer by Alan3354(69443) About Me  (Show Source):
You can put this solution on YOUR website!
in how many ways can one invite one or more of five friends to her a party?
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Peculiar wording, IMO.
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After giving it some thought:
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She can send them "snail mail"
She can text them
She can email them
She can call them on the phone
she can invite them in person
She can invite one, and have him/her invite the others
She can have her parents call their parents
She can post it on Facebook
Carrier pigeon
Announcement over the PA at school
Paint it on the back of a turtle
etc
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She can have an airplane pull a banner sign with the invites
She can put up a sign on the road
Buy a newspaper ad
Buy a magazine ad
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Or any combination of the above, and others.