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GMAT: Data sufficiency 21 (correction)

94, pg. 286. Created by Sal Khan.

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  • blobby green style avatar for user herbertpda
    The question says 300 students study French or Spanish or both. It does not say ALL students or "of all" students in the school...etc. So wouldn't we be assuming to say that if the 60 don't study Spanish then they automatically study French? How about if they study something else, like history maybe? I think statement 2 alone is sufficient. Question 1 is ambiguous, I think and I stand to be corrected please.
    (5 votes)
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    • blobby green style avatar for user daveRayel
      hello herbertpda, the 300 students who "study French or Spanish or both" is the limitation of the problem statement. Thinking of an outside subject such as History is a trap for the GMAT Data Sufficiency. At least for this question, we do not care about students who study NEITHER French nor Spanish. (This is a typical problem where, for me, the venn diagram works better than a tabular approach)

      Hope this helps :) i'll be glad to answer / help out with any follow-ups to the problem :)
      (14 votes)
  • duskpin sapling style avatar for user Angie
    The question says 300 students study French or Spanish or both. It does not say ALL students or "of all" students in the school...etc. So wouldn't we be assuming to say that if the 60 don't study Spanish then they automatically study French? How about if they study something else, like history maybe? I think statement 2 alone is sufficient. Question 1 is ambiguous, I think and I stand to be The question says 300 students study French or Spanish or both. It does not say ALL students or "of all" students in the school...etc. So wouldn't we be assuming to say that if the 60 don't study Spanish then they automatically study French? How about if they study something else, like history maybe? I think statement 2 alone is sufficient. Question 1 is ambiguous, I think and I stand to be corrected please. please so The question says 300 students study French or Spanish or both. It does not say ALL students or "of all" students in the school...etc. So wouldn't we be assuming to say that if the 60 don't study Spanish then they automatically study French? How about if they study something else, like history maybe? I think statement 2 alone is sufficient. Question 1 is ambiguous, I think and I stand to be
    (1 vote)
    Default Khan Academy avatar avatar for user

Video transcript

Problem 94. In Jefferson School, 300 students study French or Spanish or both. OK. And they have to do one of those two. If 100 of these students do not study French-- so this sounds like a Venn Diagram. Let's see. So let's say that's French. And I'll do Spanish in a different color. Let's say that is Spanish. And we have 300 students, and they study either French or Spanish. If 100 of these students do not study French-- so what did I say? This was French and this is Spanish. So 100 of these students do not study French. So this area right here is 100. Right? Those are people who study Spanish but no French at all. How many of these students study both French and Spanish? So what they want to know is the intersection of who studies French and Spanish. So that's this blue area right here. So statement number one tells us, of the 300 students, 60 do not study Spanish. So people who study French but no Spanish-- and I didn't mean they know Spanish. People who study French and do not study Spanish, that's this right here. And that's 60. Right? And let's see if we can use this information to figure out what the intersection is. So if you think about it, what we want to do is the whole universe. So the whole universe is going to be equal to the people who study-- so this 60 people plus-- we'll call that the intersection, or we could call that French and Spanish-- plus this blue area, plus this tan area. Right? That's the whole universe. And that is equal to 300. So people who study French and Spanish plus 160 is equal to 300. Subtract 160 from both sides and you get the people who study just French and Spanish. That's what? That's 240. That's 140 people who study both French and Spanish. So statement one is sufficient. Let's see what statement two gets us. Statement two tells us, a total of 240 of the students study Spanish. So in statement two, we don't know this. But we know that a total of 240 students study Spanish, right? So we know that this whole circle is 240. And if we're just trying to figure out this blue part, we just have to subtract out the tan part. So if we want to know French and Spanish, French and Spanish is going to be equal to the whole amount that study Spanish-- which they just told us, 240-- minus just the people who study only Spanish. Right? Because you could study Spanish and French. So 240 people who study Spanish minus the people who just study Spanish. So that's 100. That's that tan area. That also equals 140. So both statements individually are sufficient to answer this question. So the answer is D.