# REVENUE questions

• June 11th 2006, 12:08 PM
usm_67
REVENUE questions
Denide is an artist who works at a shopping cneter drawing "pencil potraitts". SHe charges $20 per potraite and is averaging 30 potraits per week. she decides to increase the price , but every 1 doller increase she will lose one sale per week. it takes her$10 to make one potrait. wat should she set the price to get the max. profi.
• June 11th 2006, 02:55 PM
ThePerfectHacker
Quote:

Originally Posted by usm_67
Denide is an artist who works at a shopping cneter drawing "pencil potraitts". SHe charges $20 per potraite and is averaging 30 potraits per week. she decides to increase the price , but every 1 doller increase she will lose one sale per week. it takes her$10 to make one potrait. wat should she set the price to get the max. profi.

Let $S(\Delta p)$ represent sales. Where $\Delta p$ represents the change in price. For example, if $\Delta p=1$ means that the price was increased by 1 dollar, then $S(\Delta p)$ represents the sales. Since as you said she loses a sale for each dollar you have that $S(\Delta p)=29$ because 30 without changing the price and 29 if increasing the price by 1 dollar.

We can create the first few values for $\Delta p$ and see how they affect the sales.
$\left\{ \begin{array}{cc} \Delta p&S(\Delta p)\\ 0&30\\1&29\\2&28\\3&37$
Do you see a formula? Yes,
$S(\Delta p)=30-\Delta p$.

Remember that,
$\mbox{Profit }=\mbox{ Revenue }-\mbox{ Cost}$
In this case if she has to pay $20 for each sale since there are $30-\Delta p$ sales in total we have that, $\mbox{Cost }=20(30-\Delta p)$. Now, she recieves $20+\Delta p$ for every sale, because$20 was original and she increase the price by $\Delta p$
But she makes $30-\Delta p$ sales thus in total she recieves $(20+\Delta p)(30-\Delta p)$ thus,
$\mbox{Revenue }=(20+\Delta p)(30-\Delta p)$
Finally here profit is the difference between these values thus,
$(20+\Delta p)(30-\Delta p)-20(30-\Delta p)$
Open parantheses (use FOIL and watch those signs :eek: )
$30\Delta p-(\Delta p)^2$
This is a parabola with a maximum point the max occurs at, $\Delta p=15$ in that case she has to increase her price by 15 dollars thus the new price would be 35 dollars.