Support Standard aluminum soft-drink cans do not vary in the amount of aluminum that they contain. Support 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 Support all the cans in L were recycled into cans in M and since Support the amount of material other than aluminum in an aluminum can is negligible, it follows that Conclusion M contains twice as many cans as L.
The author concludes that the M group has twice as many cans as the L group. He supports this with these claims:
(1) All standard aluminum cans have the same amount of aluminum.
(2) Half of the aluminum in the M group was recycled from used L group cans.
(3) All L group cans were recycled into M group cans.
(4) The amount of non-aluminum materials in an aluminum can is negligible.
Half the aluminum in the M group came from the L group, and all L group cans were recycled. Since all cans use the same amount of aluminum, the author concludes the M group has twice as many cans. But he assumes that all the aluminum from the L group actually ended up in the M group.
What if there were just as many cans in the L group and half the aluminum was lost during recycling? To guarantee the conclusion, we must assume that no aluminum is lost when cans are recycled.
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.
Just because the M group cans can’t be recycled further does not prove that there are twice as many M group cans as L group cans. It’s still possible that some aluminum from the L group was lost during the recycling process.
Recycled aluminum is of poorer quality than unrecycled aluminum.
Even if the M group cans are lower quality than other cans, this doesn’t prove that there are twice as many M group cans as L group cans. We still don’t know whether some aluminum was lost during recycling.
All of the aluminum in an aluminum can is recovered when the can is recycled.
In other words, no aluminum is lost when a can is recycled. Since half the aluminum in the M group came from the L group, and all L cans were recycled into M cans, and all cans use the same amount of aluminum, this guarantees the conclusion that the M group has twice as many cans.
None of the soft-drink cans in group L had been made from recycled aluminum.
This doesn’t guarantee that there are twice as many cans in the M group as the L group. Just because the L group cans were already made of recycled aluminum does not mean that no aluminum was lost when the L group cans were recycled into M group cans.
Aluminum soft-drink cans are more easily recycled than are soft-drink cans made from other materials.
The argument only addresses cans made from aluminum; cans made from other materials are irrelevant. (E) doesn’t prove that there are twice as many cans in the M group.
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