Hi Gnpth,
When it comes to Weighted Average questions, there are several different ways to go about getting to the correct answer. This question has some rather specific patterns that you can take advantage of though... so that you can avoid doing lots of math.
First off, the answer choices are "spaced out", so we can take advantage of that spread.
Second, the average of 1 box of chocolate chip cookies and 1 box of plain cookies is ($1.25 + $0.75)/2 = $1. This is important because....
Third, there are 1585 boxes of cookies with a combined value of $1588.75.....
1588.75/1585 = Just a little bit more than $1 per box
This means that SLIGHTLY MORE than half of the boxes are chocolate chip cookies. We're asked how many boxes of PLAIN cookies were sold (thus, SLIGHTLY LESS than half of those boxes were plain cookies.
Half of 1585 is about 792. Which answer is slightly less than that....?
Final Answer:
GMAT assassins aren't born, they're made,
Rich
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