# June 2007 - Sec 1 - Game 4 - Q21

## Video Transcript:

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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
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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
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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
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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
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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.