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# Ps:conundrum

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Intern
Joined: 08 May 2006
Posts: 19

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20 Aug 2006, 21:20
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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
Manager
Joined: 25 Jul 2006
Posts: 99

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20 Aug 2006, 21:26
combinations with 4 letters = 4 single + 4P2/2 = 4+ 4*3/2 = 10
combinatiosn witht 5 letters = 5 + 5P2/2 = 5 + 5*4/2 = 15

so minimum letters required = 5

OA?
20 Aug 2006, 21:26
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# Ps:conundrum

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