tom09b wrote:

I do not understand how we assume that Jefferson School has only 300 students. If this is not the total number then we cannot say anything from the statements, so answer is E. Am I right??

We are not assuming that. We are told that "in Jefferson School, 300 students study French or Spanish or both", there might be more students who study neither French nor Spanish. But this piece of information tells us that among these 300 students

there is none who study neither French nor Spanish. So,

300={French}+{Spanish}-{Both}.

In Jefferson School, 300 students study French or Spanish or both. If 100 of these students do not study French, how many of these students study both French and Spanish?Given: 300 = {French} + {Spanish} - {Both} and {Spanish} - {Both} = 100 --> 300 = {French} + 100 --> {French} = 200.

Question: {Both}=?

(1) Of the 300 students, 60 do not study Spanish --> {French} - {Both} = 60 --> 200 - {Both} = 60 --> {Both} = 140. Sufficient.

(2) A total of 240 of the students study Spanish --> {Spanish} = 240 --> 240 - {Both} = 100 ---> {Both} = 140. Sufficient.

Answer: D.

Thanks Bunuel. Now its clear.This is an interesting problem because I assumed there would be some students who study neither. But I have learnt a new way to look at these problems and read carefully to understand the exact meaning.

. - Holds True for Learning for GMAT