Problem Solving

Hi Vincen,

To start, the GMAT almost always lists the answer choices 'in order' (often from least to greatest although sometimes in decreasing order). You can sometimes take strategic advantage of that information, so it's important to make sure that you're using practice questions that follow that design pattern. That all having been said, to answer this question, we need to break the calculation down in to 'pieces' (based on the cost/discount of each piece):

The cost of the first 2,000 sheets
The cost of the next 8,000 sheets
The cost of the final 15,000 sheets

At $0.05 per sheet, the first 2,000 sheets would cost (2,000)($0.05) = $100

Since a 10% discount is applied to the TOTAL cost of the next 8,000 sheets, that cost would be....
(8,000)($0.05) = $400 - (.1)($400) = $360

A 20% discount is applied to the TOTAL cost of the final 15,000 sheets....
(15,000)($0.05) = $750 - (.2)($750) = $600

Total Cost = $100 + $360 + $600 = $1060

Final Answer: B

GMAT assassins aren't born, they're made,
Rich

Vincen wrote:If xerox paper costs 5 cents a sheet and a buyer gets 10% discount on all xerox paper one buys after the first 2000 papers and 20% discount after first 10000 papers, how much will it cost to buy 25000 sheets of xerox paper?

A. $1250
B. $1060
C. $1350
D. $900
E. $1000

The first 2,000 sheets cost 2,000 x 5 = 10,000 cents = 100 dollars.

The next 8,000 sheets cost 8,000 x 5 x 0.9 = 36,000 cents = 360 dollars.

The last 15,000 sheets cost 15,000 x 5 x 0.8 = 60,000 cents = 600 dollars.

Thus, the total for 25,000 sheets is 100 + 360 + 600 = 1,060 dollars.

Answer: B