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Joined: 16 May 2014
Posts: 592
Given Kudos: 0
GRE 1: Q165 V161
Set S contains 7 different letters
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05 May 2016, 23:58
05 May 2016, 23:58
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Question Stats:
57% (01:12) correct
42% (01:10) wrong based on 26 sessions
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Set S contains 7 different letters. How many subsets of set S, including an empty set, contain at most 3 letters?
A. 29
B. 56
C. 57
D. 63
E. 64
Note: this is a GMAT question
A. 29
B. 56
C. 57
D. 63
E. 64
Note: this is a GMAT question
Re: Set S contains 7 different letters
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14 May 2016, 03:41
14 May 2016, 03:41
Ans 64
Sent from my E20 using Tapatalk
Sent from my E20 using Tapatalk
Re: Set S contains 7 different letters
[#permalink]
14 May 2016, 03:44
14 May 2016, 03:44
Explanation
At most three 3 including empty subset means
No of empty subset+no of ways of choosing set containing(one letter in set+two letter in a set+3 letter in a set)
=1+7C1+7C2+7C3
Sent from my E20 using Tapatalk
At most three 3 including empty subset means
No of empty subset+no of ways of choosing set containing(one letter in set+two letter in a set+3 letter in a set)
=1+7C1+7C2+7C3
Sent from my E20 using Tapatalk
