Moving on to question 21: If each
recycling center in Rivertown recycles
exactly three kinds of materials then
which one of the following could be true?
Again, we know that if every single center
recycles exactly 3 from the second condition
centers 1 and 2 are going to have the
exact same three materials. Again we
know we can't have plastic in center
2 because that would place it in center
1 which violates our contdition of only
one plastic. Since 1 and 2 are the exact
same we know plastic must be in center
3. Alright now we placed plastic in center 3.
We know that plastic and glass can't be
together and we must have glass though.
Again, coming directly from the passage. Exactly
five kinds of material are recycled at
these recycling centers. So glass must be
present and therefore glass is going to
appear in both 1 and 2. Now you notice
what do we have left. For all three of these
centers the only variables remaining are
now newsprint, tin and wood. We know that if
we select wood we must have newsprint
but if we pick newsprint it's
possible that we don't have wood because again
newsprint is necessary in our first
condition. So it's possible that we have
tin. You notice regardless
in both options newsprint is going to be
present. So we know we're gonna have
newsprint in all three possibilities and
then we're gonna have reversed dual
options of wood and tin. And again you notice
your reverse dual options are between 1 and 2 and 3.
Either 1 and 2 are going to be wood
and 3 is going to be tin or 1 and 2 are
going to be tin and 3 are going to be wood. So now
looking for what could be true
(A) only center 2 recycles glass. Again
that is impossible.
Both centres wanted you must recycle
glass. (B) only center3 recycles
newsprint. Again every single center
recycle newsprint. So that is definitely out.
(C) only center 1 recycles plastic.
Again, impossible. Center 3 is
recycling plastic. (D) only center 3
recycles tin. Well that could be true
because again center 3 could
recycle tin. Centers 1 and 2 recycling
wood. So (D) could be true and (D) would be the correct
answer. Again just checking (E). Only center
1 recycles wood. Notice whatever
center 1 recycles center 2 also
recycles. Either they're both gonna be
tin or they're both gonna be wood. So
(E) cannot be true and (E) is out.