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Moving on to question 21: If each
recycling center in Rivertown recycles

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exactly three kinds of materials then
which one of the following could be true?

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Again, we know that if every single center
recycles exactly 3 from the second condition

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centers 1 and 2 are going to have the
exact same three materials. Again we

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know we can't have plastic in center
2 because that would place it in center

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1 which violates our contdition of only
one plastic. Since 1 and 2 are the exact

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same we know plastic must be in center
3. Alright now we placed plastic in center 3.

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We know that plastic and glass can't be
together and we must have glass though.

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Again, coming directly from the passage. Exactly
five kinds of material are recycled at

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these recycling centers. So glass must be
present and therefore glass is going to

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appear in both 1 and 2. Now you notice
what do we have left. For all three of these

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centers the only variables remaining are
now newsprint, tin and wood. We know that if

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we select wood we must have newsprint
but if we pick newsprint it's

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possible that we don't have wood because again
newsprint is necessary in our first

1:30

condition. So it's possible that we have
tin. You notice regardless

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in both options newsprint is going to be
present. So we know we're gonna have

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newsprint in all three possibilities and
then we're gonna have reversed dual

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options of wood and tin. And again you notice
your reverse dual options are between 1 and 2 and 3.

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Either 1 and 2 are going to be wood
and 3 is going to be tin or 1 and 2 are

2:01

going to be tin and 3 are going to be wood. So now
looking for what could be true

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(A) only center 2 recycles glass. Again
that is impossible.

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Both centres wanted you must recycle
glass. (B) only center3 recycles

2:15

newsprint. Again every single center
must

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recycle newsprint. So that is definitely out.
(C) only center 1 recycles plastic.

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Again, impossible. Center 3 is
recycling plastic. (D) only center 3

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recycles tin. Well that could be true
because again center 3 could

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recycle tin. Centers 1 and 2 recycling
wood. So (D) could be true and (D) would be the correct

2:39

answer. Again just checking (E). Only center
1 recycles wood. Notice whatever

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center 1 recycles center 2 also
recycles. Either they're both gonna be

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tin or they're both gonna be wood. So
(E) cannot be true and (E) is out.