Question

Worth 33 points each!!

Suppose you write a book. The printer charges $4 per book to print it, and you spend $3500 on advertising. You sell the book for $15 a copy. How many copies must you sell so that your income from sales is greater than your total cost?

Options:
≥ 308
≥ 319
t < 8
t ≥ -3

Answer 1

I think answer is 319

Answer 2

Where x is the number of books sold, i is income, and c is cost:

c = 4x + 3500 ($4 per book plus the 3500 flat marketing fee)

i = 15x ($15 per book)

You are looking for the point where these intersect: the intersection is where the income is equal to the cost, and at any point after that the income is greater than the cost. So, set the equations equal to each other:

4x + 3500 = 15x

subtract 4x from both sides

3500 = 11x

divide both sides by 11

x = 318.181818

So, you would have to sell a minimum of 319 books in order to make a profit.