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Ferrari: Newbie | Next Rank: 10 Posts; Posts: 2; Joined: Wed Dec 02, 2009 5:30 pm

by Ferrari » Wed Dec 02, 2009 5:37 pm

Q. In how many ways 5 rings of different types can be worn in 4 fingers?

My answer is 5*5*5*5, because one finger can wear 5 ways, similarly other three fingers.
But this is not the correct answer.

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Source: Beat The GMAT — Problem Solving | Wed Dec 02, 2009 5:37 pm

papgust: Community Manager; Posts: 1537; Joined: Mon Aug 10, 2009 6:10 pmFollowed by: 252 members; Thanked: 653 times

by papgust » Wed Dec 02, 2009 6:45 pm

IMO it should be 5*4*3*2 (If the question DOES'NT ask for repetition)

First finger has 5 rings to wear. After choosing a ring for first finger, you have four rings for the second finger. And so on.

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Stuart@KaplanGMAT: GMAT Instructor; Posts: 3225; Joined: Tue Jan 08, 2008 2:40 pmFollowed by: 614 members; Location: Toronto; Thanked: 1710 times; GMAT Score:800

by Stuart@KaplanGMAT » Wed Dec 02, 2009 7:32 pm

Ferrari wrote:Q. In how many ways 5 rings of different types can be worn in 4 fingers?

My answer is 5*5*5*5, because one finger can wear 5 ways, similarly other three fingers.
But this is not the correct answer.

Is that the entire question?

Nowhere does it say there's a minimum or maximum number of rings per finger, so we can't assume that it's one on each.

Stuart Kovinsky | Kaplan GMAT Faculty | Toronto

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Ferrari: Newbie | Next Rank: 10 Posts; Posts: 2; Joined: Wed Dec 02, 2009 5:30 pm

by Ferrari » Wed Dec 09, 2009 8:31 am

Thanks for your response.
Yes, that is all the question, there is no constraints on wearing rings.

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