Principle of Inclusion and Exclusion
In a town of 50,000 people,
28,000 people read NanJing Morning News,
23,000 people read NanJing Evening News, and
4,000 people read both.
How many people read neither?
by
tapan ambikar
Katie is teaching a class of thirty pupils, of which fourteen are girls. She knows that there are twenty-two pupils who are right-handed.
What is the minimum number of girls who are right-handed in this class?
by
Aronas Nuresi
How many positive integers less than or equal to 60 are divisible by 3, 4, or 5?
by
Paul Fournier
At a construction site, Jorge is in charge of hiring skilled workers for the project. Out of 80 candidates that he interviewed, he found that
- 45 were painters,
- 50 were electricians,
- 50 were plumbers,
- 15 had skills in all three areas, and
- all of them had skills in at least one of these areas.
If he hired everyone who was skilled in exactly 2 areas, how many candidates were hired?
by
Victor Paes Plinio
For the integers from 1 to 1000, how many multiples of 9 are also multiples of 6?
by
Arron Kau