Bunuel wrote:

Paper can be purchased for $10 per pack of 500, $3 per pack of 200 and $0.30 per 10 sheets. If one needs to purchase exactly 5640 sheets of paper, what the lowest possible price one must pay?

A. $119.20

B. $114.20

C. $110.20

D. $85.20

E. $56.20

Let’s calculate the unit (per sheet) cost of each option:

Packs of 500: unit cost = $10/500 = $0.02

Packs of 200: unit cost = $3/200 = $0.015

Single sheets: unit cost = $0.30/10 = $0.03

We see that the greatest savings occurs with packs of 200, then packs of 500, and, finally, single sheets.

Thus, to maximize savings, we should buy as many packs of 200 as possible. Since 5640/200 = 28.2, we can buy 28 packs of 200, which will cost us:

$3 x 28 = $84

So now we have 5640 - (28 x 200) = 40 sheets left. For these 40 sheets, we must buy them as single sheets, and they will cost us:

$0.03 x 40 = $1.20

Thus, the lowest possible price we have to pay is $84 + $1.20 = $85.20.

Answer: D

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Jeffery Miller

Head of GMAT Instruction

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