Question related to expected value
Thanks in advance for any help you can provide.
The question is:
A previous analysis of historical data of advertising campaigns found that the mean value of orders for promotional goods is $12.50, with the company earning a gross profit of 20% on each order. The fixed cost of conducting the four promotions next year is estimated to be $15 000, with a variable cost of $3.00 per customer for mailing and handling costs.
How large a customer base must the company have to cover the cost of the promotions?
So far I have
0.20 x $12.50 = 2.50 gross profit per item
15 000 / 2.50 = 6000 customers.
The correct answer is 9231 customers.
I don't know how to incorporate the 3.00 variable in the calculation / where I'm going wrong?
Thanks in advance,