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There are 40 people at a reception for international students. The students, boys and girls, are from Peru and China. 18 of all the students are boys, and 12 of all the students are Peruvian. 17 of the Chinese are girls. Given that a student is a boy, what is the probability that he is Chinese? A Venn diagram will help you to answer this question.

Respuesta :

18 boys so we have 22 girls! 
12 Peruvians so 28 are Chinese! 
17 out of 28 Chinese students are girls so 11 of them are Chinese boys! 
we have 17 chinese girls and totally 22 girls so 5 of the Peruvians are girls and 7 of them are boys! 

so the result is that 11 out of 18 boys are Chinese and 7 out of 18 boys are Peruvian!!! 
so the probability that a boy is Chinese = 11/18

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