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Mr.William bought a box of 15 tube lights out of which exactly 5 were

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Joined: 25 Dec 2018
Posts: 148
Location: India
GMAT 1: 490 Q47 V13
GPA: 2.86
Mr.William bought a box of 15 tube lights out of which exactly 5 were  [#permalink]

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New post 11 Jan 2019, 22:53
2
3
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A
B
C
D
E

Difficulty:

  45% (medium)

Question Stats:

64% (02:26) correct 36% (03:05) wrong based on 45 sessions

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Mr.William bought a box of 15 tube lights out of which exactly 5 were broken. He took out 4 tube lights at random. What is the probability that exactly 2 out of 4 tube lights be selected were broken?

A. 3/91
B. 13/91
C. 31/91
D. 1/13
E. 30/91
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G
Joined: 26 Dec 2018
Posts: 142
Location: India
Re: Mr.William bought a box of 15 tube lights out of which exactly 5 were  [#permalink]

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New post 11 Jan 2019, 23:47
1
Given :
Total Tubelights = 15
No. of broken Tubelights = 5 Exactly
No. of unbroken Tubelights = 10
No. of Tubelights taken out = 4

Question:
Probability of Exactly 2 out of 4 Tubelights taken out were broken =
(Probability of 2 Broken Tubelights AND Probability of 2 Unbroken Tubelights ) x Its Arrangement

= (5/15).(4/14).(10/13).(9/12).4! / (2!.2!)
= 30/91
Answer Option E is Correct..!

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Joined: 09 Mar 2018
Posts: 1002
Location: India
Re: Mr.William bought a box of 15 tube lights out of which exactly 5 were  [#permalink]

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New post 02 Feb 2019, 10:47
1
akurathi12 wrote:
Mr.William bought a box of 15 tube lights out of which exactly 5 were broken. He took out 4 tube lights at random. What is the probability that exactly 2 out of 4 tube lights be selected were broken?

A. 3/91
B. 13/91
C. 31/91
D. 1/13
E. 30/91



Total Tube lights = 15
Broken = 5
Not Broken = 10

Exactly 2 out of 4 tube lights be selected were broken
= \(\frac{{5C2 * 10C2}}{15C4}\)

= 30/91
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Re: Mr.William bought a box of 15 tube lights out of which exactly 5 were   [#permalink] 02 Feb 2019, 10:47
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Mr.William bought a box of 15 tube lights out of which exactly 5 were

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