Question

An appliance store manager estimates that for x television ads run per day, R(x)=-0.01x^3+x^2-3x+200 refrigerators will be sold per month. Find R'(4) and interpret what it tells us about sales.
My answer was for every 4 TV adds, 1.16 refrigerators will be sold. Is this correct?

Answer 1

start with the R'
R'(x)= -.03x^2+2x-3
so R'(4) = -.03(4)^2+2(4)-3 = 4.52
The function of refrigerators sold per month with x being the number of add run per day, so its derivative would be how many more refrigerators are sold (not the abolute number of fridges sold) with a change in adds per day (the slope of the fridge per ad function at a given level of adds).
.

Answer 2

Thanks