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two students chosen at random - part 2 ;)

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two students chosen at random - part 2 ;)

by fskilnik@GMATH » Wed Dec 29, 2010 10:37 am
Hi there,

From a group of students, two people will be randomly chosen simultaneously. What is the probability that two male or two female students will be selected ?

(1) The probability of selecting one male and one female student is 42%
(2) There are twice as many male students as female students

Enjoy!

Regards,
Fabio.
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Source: — Data Sufficiency |
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by anshumishra » Wed Dec 29, 2010 11:30 am
fskilnik wrote:Hi there,

From a group of students, two people will be randomly chosen simultaneously. What is the probability that two male or two female students will be selected ?

(1) The probability of selecting one male and one female student is 42%
(2) There are twice as many male students as female students

Enjoy!

Regards,
Fabio.
Cool. So this is the REAL question.

(1) Sufficient, because what we want is the complement of what was given ?

(2)
> If f = 1 and m = 2, the answer would be: (2/3)*(1/2) = 1/3
> If f= 2 and m = 4, the answer would be: (2/6)*(1/5)+(4/6)*(3/5) = 7/15

Therefore (2) is not sufficient!

Answer is A.
Thanks
Anshu

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by fskilnik@GMATH » Wed Dec 29, 2010 1:14 pm
anshumishra wrote:Cool. So this is the REAL question.

(1) Sufficient, because what we want is the complement of what was given ?

(2)
> If f = 1 and m = 2, the answer would be: (2/3)*(1/2) = 1/3
> If f= 2 and m = 4, the answer would be: (2/6)*(1/5)+(4/6)*(3/5) = 7/15

Therefore (2) is not sufficient!
PERFECT!

I´m glad you like it, Anshu.

Regards,
Fabio.
Fabio Skilnik :: GMATH method creator ( Math for the GMAT)
English-speakers :: https://www.gmath.net
Portuguese-speakers :: https://www.gmath.com.br
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