MathematicsSetsWAEC
In a class of 40 students, 25 offer Biology and 20 offer Chemistry. If every student offers at least one of the two subjects, how many offer both?
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Answer: B. 5
n(B ∪ C) = n(B) + n(C) − n(B ∩ C): 40 = 25 + 20 − x, so x = 5.
An AdmitMe practice question, written for the WAEC syllabus. Not an official past question.