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# A researcher plans to identify each participant in a certain

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Director
Joined: 08 Jul 2004
Posts: 595

Kudos [?]: 287 [0], given: 0

A researcher plans to identify each participant in a certain [#permalink]

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05 Apr 2005, 15:17
00:00

Difficulty:

45% (medium)

Question Stats:

57% (01:09) correct 43% (01:16) wrong based on 260 sessions

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A researcher plans to identify each participant in a certain medical experiment with a code consisting of either a single letter or a pair of distinct letters written in alphabetical order. What is the least number of letters that can be used if there are 12 participants, and each participant is to receive a different code?

A. 4
B. 5
C. 6
D. 7
E. 8

OPEN DISCUSSION OF THIS QUESTION IS HERE: a-researcher-plans-to-identify-each-participant-in-a-certain-134584.html
[Reveal] Spoiler: OA

_________________

Regards, S

Kudos [?]: 287 [0], given: 0

Manager
Joined: 04 Mar 2005
Posts: 106

Kudos [?]: 5 [2], given: 0

Location: NYC

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05 Apr 2005, 20:31
2
KUDOS
saurya_s wrote:
A researcher plans to identify each participant in a certain medical experiment with a code consisting of either a single letter or a pair of distinct letters written in alphabetical order. What is the least number of letters that can be used if there are 12 participants, and each participant is to receive a different code?
A. 4
B. 5
C. 6
D. 7
E. 8

Ans = B (5)

Use A, B, C,D& E as the 5 codes.
5 participants can each get one of the 5 codes.
For the remaining, use 2 code combinations from the 5 codes
10 such combinations are possible.
Hence 5 codes are suff.

Kudos [?]: 5 [2], given: 0

Senior Manager
Joined: 19 Feb 2005
Posts: 486

Kudos [?]: 25 [0], given: 0

Location: Milan Italy

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06 Apr 2005, 03:48
ssap is right. B:5
A B C D E and the first 5 are done
BC BD BE
CD CE
DE
(no more than 4!)

Kudos [?]: 25 [0], given: 0

Director
Joined: 31 Aug 2004
Posts: 606

Kudos [?]: 153 [0], given: 0

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06 Apr 2005, 04:56
Agree with 5.
Set of answers provided above explains perfectly why 6 is overestimated.

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Director
Joined: 29 Nov 2012
Posts: 863

Kudos [?]: 1484 [0], given: 543

Re: A researcher plans to identify each participant in a certain [#permalink]

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30 Dec 2012, 03:01
How to solve this one?
_________________

Click +1 Kudos if my post helped...

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Kudos [?]: 1484 [0], given: 543

Math Expert
Joined: 02 Sep 2009
Posts: 42529

Kudos [?]: 135179 [0], given: 12671

Re: A researcher plans to identify each participant in a certain [#permalink]

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30 Dec 2012, 07:42
fozzzy wrote:
How to solve this one?

Check here: a-researcher-plans-to-identify-each-participant-in-a-certain-134584.html
_________________

Kudos [?]: 135179 [0], given: 12671

Re: A researcher plans to identify each participant in a certain   [#permalink] 30 Dec 2012, 07:42
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