Problem Solving

Hi oquiella,

This question can be solved Algebraically or by TESTing THE ANSWERS.

We're told that an author receives $0.80 for each of the FIRST 100,000 copies of her book sold and $0.60 for each additional copy (after the first 100,000). We're then told that she received $260,000 in royalties. We're asked how many copies of the book were sold.

Let's TEST THE ANSWERS.

Since Answer B is only 300,000, if she received $0.80 for each of those books (even though she'd actually receive less than that once she sold over 100,000 copies), the total revenue would be only 300,000($0.80) = $240,000. This is TOO LOW, so MORE books must have been sold.

With Answer D: 400,000...

We have $0.80(100,000) = $80,000 + $0.60(300,000) = $180,000....
$80,000 + $180,000 = $260,000
This is a MATCH for what we were told, so this MUST be the answer.

Final Answer: D

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

oquiella wrote:An author received $0.80 in royalties for each of the first 100,000 copies of her book sold, and $0.60 in royalties for each additional copy sold. If she received a total of $260,000 in royalties how many copies of her book were sold?


A. 130,000
B. 300,000
C. 380,000
D. 400,000
E. 420,000

If we let n = the total number of copies sold, then (n - 100,000) is the number of additional copies (those in excess of 100,000) sold, and we can create the equation:

260,000 = 0.8 x 100,000 + 0.6(n - 100,000)

260,000 = 80,000 + 0.6n - 60,000

240,000 = 0.6n

400,000 = n

Answer: D