Question

100 students took part in a Mathematics competition consisting of four problems 90 students solved the first problem correctly 85 students solved the second problem correctly 80 students solved the third problem correctly 75 students solved the last problem correctly What is the MINIMUM number of children who could have solved all the questions correctly?

Answer 1

At least 82 students have answered correctly because if there are 100 students and on 4 problems a "total" of 330 students answered correctly, making the average 82.

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