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# From the set of numbers x, y, t, z and w, how many different

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Intern
Joined: 05 Jun 2010
Posts: 3
From the set of numbers x, y, t, z and w, how many different [#permalink]

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19 Jun 2010, 14:48
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55% (hard)

Question Stats:

56% (01:10) correct 44% (01:29) wrong based on 93 sessions

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From the set of numbers x, y, t, z and w, how many different combinations can we have without the t in them? Ex:. (x,y), (x), (w,z,y,x), etc and (x,y)=(y,x)

A. 10
B. 14
C. 15
D. 16
E. 30
[Reveal] Spoiler: OA
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Joined: 02 Sep 2009
Posts: 43898

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19 Jun 2010, 14:59
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Gusano97 wrote:
Could anybody help me with these problem?

From the set of numbers x, y, t, z and w, how many different combinations can we have without the t in them? Ex:. (x,y), (x), (w,z,y,x), etc and (x,y)=(y,x)

A)10
B)14
C)15
D)16
E)30

There are 4 letter without t: x, y, z, and w, so:
$$C^1_4+C^2_4+C^3_4+C^4_4=4+6+4+1=15$$

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22 Jun 2010, 14:23
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Another way: Any letter (x, y, z, w) can be included or not. So, we have 2^4 combinations - 1 empty combination = 15 combinations
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Joined: 09 Sep 2013
Posts: 13760
Re: From the set of numbers x, y, t, z and w, how many different [#permalink]

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22 Aug 2014, 03:08
Hello from the GMAT Club BumpBot!

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Re: From the set of numbers x, y, t, z and w, how many different [#permalink]

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10 Sep 2016, 04:31
Hello from the GMAT Club BumpBot!

Thanks to another GMAT Club member, I have just discovered this valuable topic, yet it had no discussion for over a year. I am now bumping it up - doing my job. I think you may find it valuable (esp those replies with Kudos).

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Joined: 22 May 2015
Posts: 99
Re: From the set of numbers x, y, t, z and w, how many different [#permalink]

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10 Apr 2017, 16:09
Question is to find no of combinations of x,y,z,w

Choosing only 1 letter - 4C1 ways = 4
Choosing only 2 letter - 4C2 ways = 6
Choosing only 3 letter - 4C3 ways = 4
Choosing only 4 letter - 4C4 ways = 1

Total possible combinations = 4+6+4+1 = 15
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Re: From the set of numbers x, y, t, z and w, how many different   [#permalink] 10 Apr 2017, 16:09
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