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# If set A={a,b,c,d,e}, what is the number of subsets that must include

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Math Revolution GMAT Instructor
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If set A={a,b,c,d,e}, what is the number of subsets that must include  [#permalink]

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27 Jun 2017, 01:05
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If set A={a,b,c,d,e}, what is the number of subsets that must include only 3 elements?

A. 8
B. 10
C. 12
D. 15
E. 18

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"Only $79 for 1 month Online Course" "Free Resources-30 day online access & Diagnostic Test" "Unlimited Access to over 120 free video lessons - try it yourself" Manager Joined: 23 May 2017 Posts: 235 Concentration: Finance, Accounting WE: Programming (Energy and Utilities) Re: If set A={a,b,c,d,e}, what is the number of subsets that must include [#permalink] ### Show Tags 27 Jun 2017, 01:06 Chosing 3 elements out of 5 : 5c3 = 10 = B _________________ If you like the post, please award me Kudos!! It motivates me Director Joined: 04 Dec 2015 Posts: 745 Location: India Concentration: Technology, Strategy WE: Information Technology (Consulting) If set A={a,b,c,d,e}, what is the number of subsets that must include [#permalink] ### Show Tags 27 Jun 2017, 01:21 MathRevolution wrote: If set A={a,b,c,d,e}, what is the number of subsets that must include only 3 elements? A. 8 B. 10 C. 12 D. 15 E. 18 Set A={a,b,c,d,e} Number of ways to select 3 elements from set of 5 elements $$= \frac{5!}{3!(5-3)!}$$ $$\frac{5!}{3!2!} = \frac{5 * 4* 3*2}{3*2 * 2} = 5 * 2 = 10$$. Answer (B)... _________________ Please Press "+1 Kudos" to appreciate. Manager Joined: 03 Feb 2017 Posts: 73 Location: Australia GMAT 1: 720 Q48 V40 If set A={a,b,c,d,e}, what is the number of subsets that must include [#permalink] ### Show Tags 27 Jun 2017, 05:47 Question asks how many ways can you choose 3 items out of 5 = 5C3 = 10 Answer B Math Revolution GMAT Instructor Joined: 16 Aug 2015 Posts: 8007 GMAT 1: 760 Q51 V42 GPA: 3.82 Re: If set A={a,b,c,d,e}, what is the number of subsets that must include [#permalink] ### Show Tags 29 Jun 2017, 02:59 ==> You get 5C3=5C2=(5)(4)/2!=10. The answer is b. Answer: B _________________ MathRevolution: Finish GMAT Quant Section with 10 minutes to spare The one-and-only World’s First Variable Approach for DS and IVY Approach for PS with ease, speed and accuracy. "Only$79 for 1 month Online Course"
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Re: If set A={a,b,c,d,e}, what is the number of subsets that must include  [#permalink]

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29 Jun 2017, 15:19
If set A={a,b,c,d,e}, what is the number of subsets that must include only 3 elements?

$$= 5C2$$

$$= \frac{5!}{2! * 3!}$$

$$= 5 * 2$$

$$= 10$$

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Re: If set A={a,b,c,d,e}, what is the number of subsets that must include   [#permalink] 29 Jun 2017, 15:19
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