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The probability that a visitor at the mall buys a pack of

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Intern
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Re: the prob that a visitor at the mall buys a pack of candy is  [#permalink]

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New post 24 Feb 2012, 12:48
3
6 trials
4 successes w/ prob of each success = 3/10
2 failures w/ prob of each failure = 7/10

6C4 x (3/10)^4 x (7/10)^2
=0.0595
=approximately 6%
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Re: The probability that a visitor at the mall buys a pack of  [#permalink]

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New post 12 Mar 2017, 05:06
bmwhype2 wrote:
The probability that a visitor at the mall buys a pack of candy is 0.3. If 6 visitors came to the mall today, what is the probability that exactly 4 will buy candy?


CORRECT ANSWER:
\(\frac{6!}{4!*2!}*0.3^4*0.7^2\)



Why do we have to multiply \(\frac{6!}{4!*2!}\) ?
I don't think the sequence in which people buy matters here. Does it ?

Bunuel, kindly help.
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Re: The probability that a visitor at the mall buys a pack of  [#permalink]

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New post 12 Mar 2017, 06:22
Shruti0805 wrote:
bmwhype2 wrote:
The probability that a visitor at the mall buys a pack of candy is 0.3. If 6 visitors came to the mall today, what is the probability that exactly 4 will buy candy?


CORRECT ANSWER:
\(\frac{6!}{4!*2!}*0.3^4*0.7^2\)



Why do we have to multiply \(\frac{6!}{4!*2!}\) ?
I don't think the sequence in which people buy matters here. Does it ?

Bunuel, kindly help.


Please read the whole thread before posting a question: https://gmatclub.com/forum/the-probabil ... l#p1049555
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Re: The probability that a visitor at the mall buys a pack of  [#permalink]

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New post 29 Mar 2017, 19:40
Can someone help me understand why we don't consider the combinations
So the probability is BBBBNN(B-buy N-not buying)
Therefore p(B)=3/10 p(N)=7/10
3/10^4 * 7/10 ^2 * 6!/4!*2!

Is this also the correct answer??
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Re: The probability that a visitor at the mall buys a pack of  [#permalink]

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New post 15 May 2018, 15:07
Hello from the GMAT Club BumpBot!

Thanks to another GMAT Club member, I have just discovered this valuable topic, yet it had no discussion for over a year. I am now bumping it up - doing my job. I think you may find it valuable (esp those replies with Kudos).

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Re: The probability that a visitor at the mall buys a pack of &nbs [#permalink] 15 May 2018, 15:07

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