MathNet 2018-part-01 — 181 problems (EN–VI) Question 161

A cycle of three lectures had constant success, that is, at each session there was the same number of participants. However, half of those who attended the first one never came back; one third of those who attended the second lecture attended only that one, and one quarter of those who attended the third attended neither the first nor the second. Knowing that there were 300 registered people and that each of them attended at least one lecture, determine:

a) How many people attended each lecture?

b) How many people attended all three lectures?