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GRE Prep Club Team Member
Joined: 20 Feb 2017
Posts: 2508
Given Kudos: 1053
GPA: 3.39
In a random selection of two people from a group of five—A,
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19 Mar 2020, 21:13
19 Mar 2020, 21:13
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Question Stats:
40% (00:12) correct
60% (00:51) wrong based on 20 sessions
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In a random selection of two people from a group of five—A, B, C, D, and E—what is the probability of selecting A and B?
(A) 2/5
(B) 1/5
(C) 1/10
(D) 1/15
(E) 1/20
(A) 2/5
(B) 1/5
(C) 1/10
(D) 1/15
(E) 1/20
Re: In a random selection of two people from a group of five—A,
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04 May 2020, 02:06
04 May 2020, 02:06
1
1= Picking A or B on the first pick
2=Picking or A of B on the second pick
P(1 and 2)= P(1)*P(2)
P(Selecting 2 of 5)= P(Selecting A or B out of 5 option of the first pick)*P( Selecting A or B out of the four letters that are left)
P(Selecting 2 of 5)= P(Selecting 2 of 5)*P(1/4)
¿Why first 2 our of 5 and then 1 out of four)
R/ In the first pick you could choose A or B in the second pick you already pick A or B in the first pick and you could only pick one of the two out of four possible options:
(2/5)*(1/4)= 1/10 --> Option C
2=Picking or A of B on the second pick
P(1 and 2)= P(1)*P(2)
P(Selecting 2 of 5)= P(Selecting A or B out of 5 option of the first pick)*P( Selecting A or B out of the four letters that are left)
P(Selecting 2 of 5)= P(Selecting 2 of 5)*P(1/4)
¿Why first 2 our of 5 and then 1 out of four)
R/ In the first pick you could choose A or B in the second pick you already pick A or B in the first pick and you could only pick one of the two out of four possible options:
(2/5)*(1/4)= 1/10 --> Option C
gmatclubot
Re: In a random selection of two people from a group of five—A, [#permalink]
04 May 2020, 02:06
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