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In a class of 30 students, 12 have a brother and 25 have a sister. There are 2 students who do not have any siblings. What is the probability that a student who has a brother also has a sister?

Respuesta :

Eddie1Wan

Answer:

3/10

Step-by-step explanation:

let n(B)=students who have a brother

n(S)= students who have a sister

n(U)=n(B)+n(S)+n(BUS)'-n(BnS)

30=12+25+2-n(BnS)

30=39-n(BnS)

n(BnS)=39-30=9

So 9 students have a brother and a sister

Probability=9/30=3/10

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