manarsadi6

19.08.2019 • 

Mathematics

From a class of girls and boys the probability that one student chosen at random to answer a question will be a girl is 1/3 . if four boys leave the class , the probability that a student chosen at random to answer a question will be a girl is 2/5 . how many boys and girls are there in the class before the four boys leave ?

Ответ:

cylertroutner

30.12.2021

Mathematics

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Let the no. of girls be x and boys be y
x/y=1/3
=>3x=y            (I)
now 4 boys leave the class is then
x/y-4=2/5
=>5x=2y-8
(I)=>5x=2(3x)-8
x=8
now 3x=y
=>y=24
therefore no. of girls is 8 and the no. of boy is 24
I have tried my besthope i helped

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Ответ:

AysiaRamosLee

17.09.2021

Mathematics

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You just cross multiply for example if its 2/5 and 5/6 you multiply 6 by 2 and  5  by 5 denominator multiplied by numerator pretty easy! 

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