broall wrote:

The more television children watch, the less competent they are in mathematical knowledge. More than a third of children in the United States watch television for more than five hours a day; in South Korea the figure is only 7 percent. But whereas less than 15 percent of children in the United States understand advanced measurement and geometric concept, 40 percent of South Korea children are competent in these areas. Therefore, if United States children are to do well in mathematics, they must watch less television.

Which one of the following is an assumption upon which the argument depends?

(A) Children in the United States are less interested in advanced measurement and geometric concepts than are South Korea children.

(B) South Korea children are more disciplined about doing schoolwork than are children in the United States.

(C) Children who want to do well in advanced measurement and geometry will watch less than television.

(D) A child's ability in advanced measurement and geometry increases if he or she watches less than one hour of television a day.

(E) The instruction in advanced measurement and geometric concepts available to children in the United States in not substantially worse than that available to South Korea children.

Source: LSAT

This argument is overall assuming that everything is the same between South Korea and the U.S. What if South Korea spends all of its school day on math while the U.S. is more of a liberal arts type of education. Also, this argument is assuming that the same people who watch TV for 5+ hours a day are not the same people that excel in math. What if it just so happens that they do both? In addition, there is a really interesting shift from "understanding advanced measurement and geometric concepts" to "doing well in mathematics." It seems to me that this goes from a specific skill to a general knowledge

The first sentence looks like a fact, but ultimately I think LSAC intended it as a claim we could attack (since the conclusion says something similar).

In any modern test, I think the second sentence would start with "After all" / "To see this", etc., so that we would know that the first sentence is a subsidiary conclusion we can attack.

- notice the gap between adv meas / geom concepts vs. 'doing well in mathematics'.

We could have easily seen a correct answer say something like

(A) one's ability to understand advanced measurement and geometric concepts is relevant to whether one is doing well in mathematics

For (C), it doesn't literally say the same thing as the conclusion, but I agree that it feels close enough to think, "Hmmm, this doesn't seem to be addressing a gap or ruling out a potential objection".

(C) is focused on children's self-directed efforts to watch less television. It's saying that the kids who really want to do well in math will take it upon themselves to watch less TV.

The author doesn't have to assume that. He's free to make his conclusion while assuming that we will have to tear all kids kicking and screaming away from the television.

(not to nerd out here, but I'm not in love with the correct answer.

If I say, "to win that tennis tournament, Ben is going to have to improve his serve", it doesn't weaken that claim at all to point out that his serve isn't the only problem: his backhand and net game are also struggling. Similarly, the fact that (E) points out a gap in instructional quality in the US vs. South Korea doesn't really affect the claim that excessive TV watching is hurting US students. More than one thing can concurrently be hurting US students. So as I said at the outset, the writing of this question is pretty loose by modern standards)

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The above is an explanation by an

MGMAT instructor.

In the conclusion, watching less television is a necessary condition for "United States children... well in maths", but it is not a sufficient condition.

If we change the conclusion from

Therefore, if United States children are to do well in mathematics, they must watch less television.

TO -

If US children watch less television, then they will do well in maths.

Now, since "watching less television" is a sufficient condition, so won't option E be a better assumption?

AjiteshArun ,

mikemcgarry ,

GMATNinja ,

ChiranjeevSingh , other experts -- please enlighten .

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