In a class 85% of the student received the highest grade in English Literature, 80% in Math, 75% in History, and 30% in Chemistry. About what percentage of the students could you say for sure that they received the highest grade in all 4 subjects?

i am pretty sure it is 67.5% cause

85/100 + 80/100+ 75/100+30/100= 270/400 and 240 divided by 400 is 0.675 0r 67.5%

I get 0% that we can say for sure got all four.

Here's how I work it out.

Between English (85%) and Mathematics (80%), the students total 165%, so there must be at least 65% who got the highest marks in both.
If we proceed this way, we can build a table of the minimum overlap between two subjects.
Subj Engl Math Hist Chem
Engl 85
Math 65___80
Hist 60___55___75
Chem 15___10___5____30

Proceeding in the same manner, we find that
Math+English=65%
History+English=60%
Total = 125%
So at least 25% have all three.

Students who excel in Chemistry (30%) can easily fit outside of the 25% who have all three, which means that we cannot say for sure that there is anyone who have all four.

We will suggest the chemistry teachers to work harder!!

Here's a Venn diagram for three subjects Maths, History and English.
http://img131.imageshack.us/img131/6307/1255641485.jpg

To determine the percentage of students who received the highest grade in all four subjects, we need to consider the subject with the lowest percentage of students receiving the highest grade. In this case, chemistry has the lowest percentage with 30%.

Since the percentage of students with the highest grade in chemistry represents the upper limit for the percentage of students who could achieve the highest grade in all subjects, we can conclude that the maximum percentage of students who received the highest grade in all four subjects would be 30%.

Therefore, we can say for sure that the percentage of students who received the highest grade in all four subjects is 30% or less.