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.
Argument or facts? Clearly we have an argument. The conclusion that 'it follows', our structural
indicator. So M contains twice as many cans as L. And how do we know that?
Well it tells us that fifty percent of the aluminum contained in a certain group (M). So, fifty
percent of the aluminum in M was recycled from another group L
of used standard aluminum soft drink cans. So we recycled L to make fifty percent of M. And then obviously the other 50%
of (M) would be from something else. So that's what M is composed of. But now
they're telling us that M is twice as many cans as L. So imagine L is X then M
has 2X the amount of cans. So now that we have a clear understanding of this passage, again these would
be the premises for the conclusion that M contains twice as many cans as L. You
notice that this is flawed logic. This argument doesn't make any sense.
The premise does not support this conclusion. And the question stem points that out by saying that
conclusion of the argument follows logically if which of the following is
Again, 'follows logically if'... We have a strengthen with sufficient premise question stem. So we are trying to guarantee
the conclusion that M contains twice as many cans as L
based on the premise that 50% of M came from recycling the cans in
L. So let's take a look at (A): The aluminum in the cans of M cannot be recycled any
further. That is completely irrelevant. It doesn't even strengthen this argument. So
(A) is out. How does that help?
(B) Recycled aluminum is of poorer quality than unrecycled aluminum. Again does not
even strengthen this argument. What difference does that make? This is not an
argument about the quality of the cans in M or L it's about the quantity. (C) all of the
aluminum in an aluminum can is recovered when the can is recycled. Well if that's true then
this 50% of M that came from L if L was X then all of the aluminum in an aluminum can is
recovered when it's recycled. Again let's not forget that we recycled L into M.
Well therefore, this 50% of M must be X. And if 50% of M is X then twice that would be 2X.
You notice that would guarantee our conclusion. So (C) here would be correct
answer. Again 100% guarantees the conclusion that M contains twice as many
cans as L because if all of the aluminum in an aluminum can is recovered when
recycled. And we recycled L and it gave us 50%. Well then M contains twice as many
But again just making sure... (D) none of the soft drink cans in group L had been made
from recycled aluminum. Again completely irrelevant. So (D) would be out. Then
lastly checking (E): Aluminum soft-drink cans are more easily recycled than are
soft drink cans made from other materials. Again, what difference does that make?
It's not about the ease of recycling it's about whether M contains twice as many cans
as L. And again on a strengthen with sufficient premise we are trying to
guarantee that conclusion