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

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

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New post 19 Jun 2010, 15:48
2
3
00:00
A
B
C
D
E

Difficulty:

  55% (hard)

Question Stats:

56% (01:12) correct 44% (01:31) wrong based on 98 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
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Re: Combination problem [#permalink]

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New post 19 Jun 2010, 15:59
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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:
\(C^1_4+C^2_4+C^3_4+C^4_4=4+6+4+1=15\)

Answer: C.
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Re: Combination problem [#permalink]

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New post 22 Jun 2010, 15:23
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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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Re: From the set of numbers x, y, t, z and w, how many different [#permalink]

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New post 10 Apr 2017, 17:09
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, 17:09
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