Suppose U is a set containing 75 elements and that A1, A2, A3 and A4 are subsets of U such that each subset Ai contains 28 elements, the intersection of any two of the four subsets contains 12 elements, the intersection of any three of the four subsets contains 5 elements, and the intersection of all four subsets contains 1 element.

a. What is |A1 ∪ A2 ∪ A3 ∪ A4|?
b. How many elements belong to exactly two of the four subsets?

6. tim is trying to study but hours go by and he doesn't get anything done. what time management advice would tim? work in smaller chunks of time an hour or less whenever you have a few minutes to spare. create flashcards. talk to your instructor right away and make a plan together for how you can get back on track, take scheduled breaks only or allow yourself only 5-10 minute breaks find somewhere quiet like a library or school to study tum off your phone and/or tell others you are busy