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There are n students in a class. Of them, k boys and k girls (including Harvey and Jessica) are selected for a dance performance in which students will dance in pairs of one boy and one girl. What is the probability that Harvey will be paired with Jessica?

(1) Other than Harvey, 5 boys are selected for the dance.

(2) 8 of the k boys are not selected for the dance.

There are n students in a class. Of them, k boys and k girls (including Harvey and Jessica) are selected for a dance performance in which students will dance in pairs of one boy and one girl. What is the probability that Harvey will be paired with Jessica?

(1) Other than Harvey, 5 boys are selected for the dance.

(2) 8 of the k boys are not selected for the dance.

Kudos for a correct solution.

ans A.. 1) statement tells us k=6. sufficient 2) statement 2 not clear as k boys are selected how can 8 out of them not selected... it must be n and not k...insufficient
_________________

Re: There are n students in a class. Of them, k boys and k girls (includin [#permalink]

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29 Jan 2015, 11:33

chetan2u wrote:

Bunuel wrote:

There are n students in a class. Of them, k boys and k girls (including Harvey and Jessica) are selected for a dance performance in which students will dance in pairs of one boy and one girl. What is the probability that Harvey will be paired with Jessica?

(1) Other than Harvey, 5 boys are selected for the dance.

(2) 8 of the k boys are not selected for the dance.

Kudos for a correct solution.

ans A.. 1) statement tells us k=6. sufficient 2) statement 2 not clear as k boys are selected how can 8 out of them not selected... it must be n and not k...insufficient

chetan2u, would you mind explaining how do you get that the answer is A? Statement (1) just gives us k, but we still don't know n... Or k is enough information to tell that the probability of Harvey paired with Jessica is 1/6?

There are n students in a class. Of them, k boys and k girls (including Harvey and Jessica) are selected for a dance performance in which students will dance in pairs of one boy and one girl. What is the probability that Harvey will be paired with Jessica?

(1) Other than Harvey, 5 boys are selected for the dance.

(2) 8 of the k boys are not selected for the dance.

Kudos for a correct solution.

ans A.. 1) statement tells us k=6. sufficient 2) statement 2 not clear as k boys are selected how can 8 out of them not selected... it must be n and not k...insufficient

chetan2u, would you mind explaining how do you get that the answer is A? Statement (1) just gives us k, but we still don't know n... Or k is enough information to tell that the probability of Harvey paired with Jessica is 1/6?

hi victorija.... as k boys and girls are already selected so k in itself becomes a certainity and n does not have any role in calculating probability..
_________________

Re: There are n students in a class. Of them, k boys and k girls (includin [#permalink]

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01 Feb 2015, 15:23

1

This post received KUDOS

Bunuel wrote:

There are n students in a class. Of them, k boys and k girls (including Harvey and Jessica) are selected for a dance performance in which students will dance in pairs of one boy and one girl. What is the probability that Harvey will be paired with Jessica?

(1) Other than Harvey, 5 boys are selected for the dance.

(2) 8 of the k boys are not selected for the dance.

Kudos for a correct solution.

Statement 1: Harvey plus 5 boys = K. So K is 6...so there are six boys and six girls...can calculate probability of one particular pairing. Sufficient.

Statement 2: Unclear. Question states K boys and K girls are selected for the dance...this statement says 8 of those K boys are not selected. Doesn't make any sense to me.

Going with A.
_________________

"Hardwork is the easiest way to success." - Aviram

One more shot at the GMAT...aiming for a more balanced score.

There are n students in a class. Of them, k boys and k girls (including Harvey and Jessica) are selected for a dance performance in which students will dance in pairs of one boy and one girl. What is the probability that Harvey will be paired with Jessica?

(1) Other than Harvey, 5 boys are selected for the dance.

(2) 8 of the k boys are not selected for the dance.

There are k boys and k girls selected (including Harvey and Jessica). Harvey can be paired with any one of the k girls. Jessica is one of the girls. The probability that Harvey will be paired with Jessica is 1/k. Notice that n has no role to play here. The required probability only needs the value of k.

Statement 1: We now know that total 5+1 = 6 boys and 6 girls were selected for the dance. So probability that Harvey will be paired with Jessica is 1/6. Sufficient.

Statement 2: This tells us that Total number of boys – k = 8. We don’t know the value of k. Not sufficient.

Re: There are n students in a class. Of them, k boys and k girls (includin [#permalink]

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04 Feb 2015, 11:49

Bunuel wrote:

Bunuel wrote:

There are n students in a class. Of them, k boys and k girls (including Harvey and Jessica) are selected for a dance performance in which students will dance in pairs of one boy and one girl. What is the probability that Harvey will be paired with Jessica?

(1) Other than Harvey, 5 boys are selected for the dance.

(2) 8 of the k boys are not selected for the dance.

There are k boys and k girls selected (including Harvey and Jessica). Harvey can be paired with any one of the k girls. Jessica is one of the girls. The probability that Harvey will be paired with Jessica is 1/k. Notice that n has no role to play here. The required probability only needs the value of k.

Statement 1: We now know that total 5+1 = 6 boys and 6 girls were selected for the dance. So probability that Harvey will be paired with Jessica is 1/6. Sufficient.

Statement 2: This tells us that Total number of boys – k = 8. We don’t know the value of k. Not sufficient.

Answer (A)

I think veritas made a mistake. Number (2) clearly should be 8 of the n boys.

Re: There are n students in a class. Of them, k boys and k girls (includin [#permalink]

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09 Feb 2015, 07:28

1

This post received KUDOS

Bunuel wrote:

Bunuel wrote:

There are n students in a class. Of them, k boys and k girls (including Harvey and Jessica) are selected for a dance performance in which students will dance in pairs of one boy and one girl. What is the probability that Harvey will be paired with Jessica?

(1) Other than Harvey, 5 boys are selected for the dance.

(2) 8 of the k boys are not selected for the dance.

There are k boys and k girls selected (including Harvey and Jessica). Harvey can be paired with any one of the k girls. Jessica is one of the girls. The probability that Harvey will be paired with Jessica is 1/k. Notice that n has no role to play here. The required probability only needs the value of k.

Statement 1: We now know that total 5+1 = 6 boys and 6 girls were selected for the dance. So probability that Harvey will be paired with Jessica is 1/6. Sufficient.

Statement 2: This tells us that Total number of boys – k = 8. We don’t know the value of k. Not sufficient.

Answer (A)

I agree with A and the explanations.

What I would like to ask refers to the part in red. If we have 6 boys and 6 girls that will be paired together, don't we have 6*6=36 combinations of possibl pairs? So, 36 possible, different pairs? Out of these 36 pairs, Harvey and Jessica together would make one pair. So, isn't the probability 1/36?

There are n students in a class. Of them, k boys and k girls (including Harvey and Jessica) are selected for a dance performance in which students will dance in pairs of one boy and one girl. What is the probability that Harvey will be paired with Jessica?

(1) Other than Harvey, 5 boys are selected for the dance.

(2) 8 of the k boys are not selected for the dance.

There are k boys and k girls selected (including Harvey and Jessica). Harvey can be paired with any one of the k girls. Jessica is one of the girls. The probability that Harvey will be paired with Jessica is 1/k. Notice that n has no role to play here. The required probability only needs the value of k.

Statement 1: We now know that total 5+1 = 6 boys and 6 girls were selected for the dance. So probability that Harvey will be paired with Jessica is 1/6. Sufficient.

Statement 2: This tells us that Total number of boys – k = 8. We don’t know the value of k. Not sufficient.

Answer (A)

I agree with A and the explanations.

What I would like to ask refers to the part in red. If we have 6 boys and 6 girls that will be paired together, don't we have 6*6=36 combinations of possibl pairs? So, 36 possible, different pairs? Out of these 36 pairs, Harvey and Jessica together would make one pair. So, isn't the probability 1/36?

hi pacifist, selection of harvey is already sure as he is one of the k boys selected.. And he can be paired with any of the 6(k) girls... so it will be 1/6..

1/36 would have been correct in following scenarios.. 1) there are 6 boys and 6 girls. Out of these one boy and one girl are to be choosen as a pair for dance. what is the prob of choosing harvey and jessica? 2) there are 6 boys, harvey being one of them. these 6 boys are to be paired with one of 36 girls, jessica being one of them.what is the prob of harvey being paired with jessica?
_________________

Re: There are n students in a class. Of them, k boys and k girls (includin [#permalink]

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09 Feb 2015, 07:48

Oh great chetan2u, thank you very much. I actually thought we were talking about the first of the 2 possibilities you provided as an example of a 1/36 probability. Kudos for your help.

Re: There are n students in a class. Of them, k boys and k girls (includin [#permalink]

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17 Nov 2016, 10:52

Hi,

I have one doubt in the question. Option A mentions that Harvey is selected, and we can correctly conclude that there are 6 boys and 6 girls selected. But how can we come to the conclusion that Jessica is among these 6 girls. Am I on a wrong track here?

Re: There are n students in a class. Of them, k boys and k girls (includin [#permalink]

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03 Dec 2016, 04:28

AnkurBansal89 wrote:

Hi,

I have one doubt in the question. Option A mentions that Harvey is selected, and we can correctly conclude that there are 6 boys and 6 girls selected. But how can we come to the conclusion that Jessica is among these 6 girls. Am I on a wrong track here?

Regards,

Ankur

Dear Ankur,

We are being told that there are K girls and K boys including Jessica and Harvey out of which we need to select pair for dance performance (one girl can be paired with one boy). Now, statement 1 tells us that a total of 6 boys are selected (including Harvey). Now, this tells us that the total number of girls is also 6 as the question stem tells us that equal number of girls and boys are selected (k) and stem also tells us that Harvey is one of those 6 girls (the question stem tells us that there are K girls and boys including Harvey and Jessica. This means that both of them are included in k). Does that help ?
_________________

Re: There are n students in a class. Of them, k boys and k girls (includin [#permalink]

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21 Mar 2017, 01:24

Statement 2 is not well phrased. I lost time trying to understand what was meant. Cheers.
_________________

What was previously considered impossible is now obvious reality. In the past, people used to open doors with their hands. Today, doors open "by magic" when people approach them

Re: There are n students in a class. Of them, k boys and k girls (includin [#permalink]

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28 Apr 2017, 16:37

Bunuel wrote:

Bunuel wrote:

There are n students in a class. Of them, k boys and k girls (including Harvey and Jessica) are selected for a dance performance in which students will dance in pairs of one boy and one girl. What is the probability that Harvey will be paired with Jessica?

(1) Other than Harvey, 5 boys are selected for the dance.

(2) 8 of the k boys are not selected for the dance.

There are k boys and k girls selected (including Harvey and Jessica). Harvey can be paired with any one of the k girls. Jessica is one of the girls. The probability that Harvey will be paired with Jessica is 1/k. Notice that n has no role to play here. The required probability only needs the value of k.

Statement 1: We now know that total 5+1 = 6 boys and 6 girls were selected for the dance. So probability that Harvey will be paired with Jessica is 1/6. Sufficient.

Statement 2: This tells us that Total number of boys – k = 8. We don’t know the value of k. Not sufficient.

Answer (A)

Bunuel I could not understand why we need total number of boys - k?
_________________

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“Strength doesn’t come from what you can do. It comes from overcoming the things you once thought you couldn’t.”

"Each stage of the journey is crucial to attaining new heights of knowledge."

There are n students in a class. Of them, k boys and k girls (including Harvey and Jessica) are selected for a dance performance in which students will dance in pairs of one boy and one girl. What is the probability that Harvey will be paired with Jessica?

(1) Other than Harvey, 5 boys are selected for the dance.

(2) 8 of the k boys are not selected for the dance.

There are k boys and k girls selected (including Harvey and Jessica). Harvey can be paired with any one of the k girls. Jessica is one of the girls. The probability that Harvey will be paired with Jessica is 1/k. Notice that n has no role to play here. The required probability only needs the value of k.

Statement 1: We now know that total 5+1 = 6 boys and 6 girls were selected for the dance. So probability that Harvey will be paired with Jessica is 1/6. Sufficient.

Statement 2: This tells us that Total number of boys – k = 8. We don’t know the value of k. Not sufficient.

Answer (A)

Bunuel I could not understand why we need total number of boys - k?

What do you mean why we need this? This is what the second statement is saying. It's not sufficient but it is what it is telling us.
_________________

There are n students in a class. Of them, k boys and k girls (including Harvey and Jessica) are selected for a dance performance in which students will dance in pairs of one boy and one girl. What is the probability that Harvey will be paired with Jessica?

(1) Other than Harvey, 5 boys are selected for the dance.

(2) 8 of the k boys are not selected for the dance.

There are k boys and k girls selected (including Harvey and Jessica). Harvey can be paired with any one of the k girls. Jessica is one of the girls. The probability that Harvey will be paired with Jessica is 1/k. Notice that n has no role to play here. The required probability only needs the value of k.

Statement 1: We now know that total 5+1 = 6 boys and 6 girls were selected for the dance. So probability that Harvey will be paired with Jessica is 1/6. Sufficient.

Statement 2: This tells us that Total number of boys – k = 8. We don’t know the value of k. Not sufficient.

Answer (A)

I think there's an issue with statement 2.

On the GMAT, the two statements in a Data Sufficiency (DS) question will never contradict each other. For example, the following question would never be a legitimate DS question:

What is the value of x" (1) x + 1 = 5 (2) 2x = 6

Here, statement 1 tells us that x = 4, and statement 2 tells us that x = 3 As such, this question does not adhere to the format of official DS questions.

In the original question, we learned (from statement 1) that k = 6 So, statement 2 is basically telling us that "8 of the 6 boys are not selected for the dance," and this contradicts the information provided in statement 1.