TeymurHajiyev wrote:

Students in certain group know either English or French or both. If 20% of those who know English do not know French, and 60% of those who know French know English, what part of the group knows both languages?

Sorry guys, for constantly bothering you with this overlapping sets things. I promise, this would be the last one

Hi,

Again, venn diag would make it easy to comprehend..

let students who Know only english =E..

let students who Know only french =F..

let students who Know both english and french = B..

total =E+F+B..

1) If 20% of those who know English do not know French..

this means that 30% of students knowing english is B..

E=.2(E+B)...

2B=8E..

\(E=B/4\)...(i)

2)60% of those who know French know English

this means that 60% of students knowing French is B.

B=.6(F+B)..

\(F=\frac{4B}{6}\)..(ii)

add values found in (i) and (ii) in total..

so \(Total=E+F+B=\frac{B}{4}+ \frac{4B}{6} + B= \frac{23}{12} * B\)...

so \(\frac{23}{12} * B=T\)...

B=

12/23 of total... ans

Doesn't matter .. you can ask till you clear your doubts...

someone will surely answer them

_________________

Absolute modulus :http://gmatclub.com/forum/absolute-modulus-a-better-understanding-210849.html#p1622372

Combination of similar and dissimilar things : http://gmatclub.com/forum/topic215915.html