IB数学例题解析及练习Conditional probabilities

今日知识点：

Conditional probabilities

例题

Q： A group of girls at a school is entered for Advanced Level Mathematics modules. Each girl takes only module M1 or only module M2 or both M1 and M2.

The probability that a girl is taking M2 given that she is taking M1 is 1/5

The probability that a girl is taking M1 given that she is taking M2 is 1/3

Find the probability that a girl selected at random is taking both M1 and M2.

解析

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Your turn

In a certain college

65% of the students are full-time students,

55% of the students are female,

35% of the students are male full-time students.

Find the probability that a student chosen at random from all the female students in the college is a part-time student.

Correct Answer： 0.45