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Two students are selected from a class of 5 girls and 12 boys

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kawal27
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Two students are selected from a class of 5 girls and 12 boys [#permalink] New post   19 Sep 2020, 00:49
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Two students are selected from a class of 5 girls and 12 boys .Find the probability that a particular pair of girl and boy is selected.

A) 1/136
B)1/63
C)1/51
D)10/21
E)13/61
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nick1816
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Re: Two students are selected from a class of 5 girls and 12 boys [#permalink] New post   19 Sep 2020, 02:29
Number of ways to select 2 students out 17 = 17C2
Number of ways to select a particular girl and boy = 2C2

Probability = 2C2/17C2 = 1/136

kawal27 wrote:
Two students are selected from a class of 5 girls and 12 boys .Find the probability that a particular pair of girl and boy is selected.

A) 1/136
B)1/63
C)1/51
D)10/21
E)13/61
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Re: Two students are selected from a class of 5 girls and 12 boys [#permalink] New post   19 Sep 2020, 03:02
nick1816 wrote:
Number of ways to select 2 students out 17 = 17C2
Number of ways to select a particular girl and boy = 2C2

Probability = 2C2/17C2 = 1/136

kawal27 wrote:
Two students are selected from a class of 5 girls and 12 boys .Find the probability that a particular pair of girl and boy is selected.

A) 1/136
B)1/63
C)1/51
D)10/21
E)13/61


nick1816 :- Why "Number of ways to select a particular girl and boy = 2C2"? What does selecting a particular girl and boy mean?
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Re: Two students are selected from a class of 5 girls and 12 boys [#permalink] New post   19 Sep 2020, 07:21
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That we have girls and boys here is irrelevant, because we're making selections from the entire group. We just need to pick two specific people. On our first selection, there is a 2/17 chance we'll pick one of the two people we want. On the next selection, there is a 1/16 chance we'll pick the remaining person we want. So the answer is (2/17)(1/16) = 1/136.
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Re: Two students are selected from a class of 5 girls and 12 boys [#permalink] New post   19 Sep 2020, 08:20
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Total: 17

To be selected: 2

Total outcomes: \(^{17}{C_2}\) = 136

Two particular people [1 girl and 1 boy]: 2

Both to be selected:Desired outcome: \(^2{C_2}\) = 1

Probability: \(\frac{Desired outcome}{ Total outcome}\)

=> \(\frac{1 }{ 136}\)

Answer A
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Re: Two students are selected from a class of 5 girls and 12 boys [#permalink] New post   14 Apr 2024, 06:59
Hello from the GMAT Club BumpBot!

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Re: Two students are selected from a class of 5 girls and 12 boys [#permalink]
14 Apr 2024, 06:59
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