Question

In a survey of 100 students, 15 students were taking algebra, biology and
chemistry, 25 were taking algebra and biology, 30 were taking algebra and
chemistry, 22 were taking biology and chemistry, 5 were only taking
algebra, 4 were only biology and 6 were taking only chemistry. If a student
is chosen at random, what is the probability of the students is taking
algebra, given that s/he is taking biology?

Answer 1

The probability of the students is taking algebra, given that s/he is taking biology

$$P(AB) = \frac{25 + 15}{100} = 0.4 = 40\%$$