June 2007 PrepTest, Section 2, Question 13
Standard aluminum soft-drink cans do not vary in the amount of aluminum that they contain. Fifty percent of the aluminum contained in a certain group (M) of standard aluminum soft-drink cans was recycled from another group (L) of used, standard aluminum soft-drink cans. Since all the cans in L were recycled into cans in M and since the amount of material other than aluminum in an aluminum can is negligible, it follows that M contains twice as many cans as L.
Standard aluminum soft-drink cans do not vary in the amount of aluminum that they contain. Fifty percent of the aluminum contained in a certain group (M) of standard aluminum soft-drink cans was recycled from another group (L) of used, standard aluminum soft-drink cans. Since all the cans in L were recycled into cans in M and since the amount of material other than aluminum in an aluminum can is negligible, it follows that M contains twice as many cans as L.
Standard aluminum soft-drink cans do not vary in the amount of aluminum that they contain. Fifty percent of the aluminum contained in a certain group (M) of standard aluminum soft-drink cans was recycled from another group (L) of used, standard aluminum soft-drink cans. Since all the cans in L were recycled into cans in M and since the amount of material other than aluminum in an aluminum can is negligible, it follows that M contains twice as many cans as L.
Standard aluminum soft-drink cans do not vary in the amount of aluminum that they contain. Fifty percent of the aluminum contained in a certain group (M) of standard aluminum soft-drink cans was recycled from another group (L) of used, standard aluminum soft-drink cans. Since all the cans in L were recycled into cans in M and since the amount of material other than aluminum in an aluminum can is negligible, it follows that M contains twice as many cans as L.
The conclusion of the argument follows logically if which one of the following is assumed?
The aluminum in the cans of M cannot be recycled further.
Recycled aluminum is of poorer quality than unrecycled aluminum.
All of the aluminum in an aluminum can is recovered when the can is recycled.
None of the soft-drink cans in group L had been made from recycled aluminum.
Aluminum soft-drink cans are more easily recycled than are soft-drink cans made from other materials.
Explanations
Wow, this took me more than one read-through. But basically, here’s what we have:
(1) soda cans have the same amount of metal each time
(2) Group L recycled its used soda cans to help Group M (50% of the metal from M was from L)
(3) All cans in L were recycled into M cans
(4) only worry about metal—the other components in a soda can are negligible (meaning, not worth considering)
Conclusion: M has twice as many cans as L
This seems to cover everything, but it’s missing one tiny piece: the recycling process. What if some (or a significant amount) of metal is lost during the recycling process?
This is just not relevant.
Quality is not even discussed.
Yup, this is the missing piece. If this weren’t true, then it wouldn’t be “twice as many”—it would be less than twice as many.
It doesn’t matter if they were.
It doesn’t matter if they are easier to recycle.
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