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If you test 2 different lightbulbs from a box of 100 bulbs that contai

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If you test 2 different lightbulbs from a box of 100 bulbs that contai [#permalink]

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New post 30 Oct 2017, 22:59
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Difficulty:

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Question Stats:

64% (00:35) correct 36% (00:43) wrong based on 47 sessions

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If you test 2 different lightbulbs from a box of 100 bulbs that contains 1 defective bulb what is the probability that both lightbulbs that you test are defective?

(A) 0
(B) 0.0001
(C) 1/9,900
(D) 0.01
(E) 1/99
[Reveal] Spoiler: OA

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Re: If you test 2 different lightbulbs from a box of 100 bulbs that contai [#permalink]

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New post 31 Oct 2017, 06:02
If box contains only 1 defective lightbulb, then the probability that one can pick out 2 different defective lightbulbs is zero.
Answer A.

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Re: If you test 2 different lightbulbs from a box of 100 bulbs that contai [#permalink]

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New post 31 Oct 2017, 06:15
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In 100 lightbulbs, only 1 bulb is defective => You never choose 2 bulbs which are both defective. Therefore, probability should be zero.
Answer A.

Please kudo if it helps.

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Re: If you test 2 different lightbulbs from a box of 100 bulbs that contai [#permalink]

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New post 31 Oct 2017, 07:23
Bunuel wrote:
If you test 2 different lightbulbs from a box of 100 bulbs that contains 1 defective bulb what is the probability that both lightbulbs that you test are defective?

(A) 0
(B) 0.0001
(C) 1/9,900
(D) 0.01
(E) 1/99

From the highlighted parts it is clear that both Light bulbs can not be defective at the same time, thus answer must be (A) 0
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Re: If you test 2 different lightbulbs from a box of 100 bulbs that contai [#permalink]

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New post 01 Nov 2017, 16:08
Bunuel wrote:
If you test 2 different lightbulbs from a box of 100 bulbs that contains 1 defective bulb what is the probability that both lightbulbs that you test are defective?

(A) 0
(B) 0.0001
(C) 1/9,900
(D) 0.01
(E) 1/99


Since there is only one defective bulb, the probability of testing two defective bulbs is zero.

Answer: A
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Re: If you test 2 different lightbulbs from a box of 100 bulbs that contai   [#permalink] 01 Nov 2017, 16:08
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