A certain stock exchange designates each stock with one, two : Quant Question Archive [LOCKED]
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# A certain stock exchange designates each stock with one, two

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A certain stock exchange designates each stock with one, two [#permalink]

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26 Apr 2006, 01:33
This topic is locked. If you want to discuss this question please re-post it in the respective forum.

A certain stock exchange designates each stock with one, two or three letter code, where each letter is selected from 26 letters of the alphabet. If the letters may be repeated and if the same letters used in a different order constitute a different code, how many different stocks is it possible to uniquely designate with these codes?

2951
8125
15600
16302
18278
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26 Apr 2006, 01:57

for 3 letters

we have 26x26x26 combinations!

for 2, we have 26x26
for 1, we have 26

Adding all of them = 18278.
Hence, E
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26 Apr 2006, 12:08
Hey,

a similar one you may hit upon, when the codes can be 4 letters OR 5 letters - answer is (26)^4*27.
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26 Apr 2006, 17:45
The number of ways to pick a 3 letter code = 26^3
The number of ways to pick a 2 letter code = 26^2
The number of ways to pick a 1 letter code = 26

Total = 26^3 + 26^2 + 26 = 26(26^2 + 26 + 1) = 18278
26 Apr 2006, 17:45
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