The derivative of x^3 is 3x^2.... is that what you were looking for?
50,000 / 2500 = 20....he bought them for 20 bucks a piece. So if he wants to sell them at 15% profit, he would sell them for 20 + 0.15(20) = $ 23 bucks.
A 15% profit of 50,000 dollars is 0.15(50,000) = 7500. Plus the 50 grand spent totals 57500. So they want to make a $ 7500 profit. Selling 2500 lamps at $ 23 per lamp (2500 x 23 = 57500) makes them their profit.
I should just shut up now...answer is $ 23 per lamp
Area of sector=fraction of sector times area of circle
fraction of sector=degrees/360
and area of circle=pir^2
so
hold a sec, we have the wiper on the outside, so we want to find the outside ring thing
do
area big sector-area small sector
or even better
(degrees/360) times (area big-areasmall)
big is 10
small is 4 (10-6=4)
areabig=10^2 times pi or 100pi
areasmall=4^2 times pi or 16pi
areabig-areasmall=100pi-16pi=84pi
then find the fraction
84pi times (150/360)=35pi square inches
