Ben K. answered 05/14/16
Tutor
4.9
(223)
JHU Grad specializing in Math and Science
Revenue is a function, just like everything else that you've seen so far in calculus. How do we find the maximum of a function? We take the derivative and set it equal to zero. Why? because at a max or min, the slope of the function is zero.
R(x) = -2 x2 + 103x
R'(x) = -4x + 103
Set that equal to zero...
-4x +103 = 0
103 = 4x
103/4 = x
x = 25.75 ~ 26, as the problem asked us to round to the nearest whole number.
Thus, they need to sell 26 hearing aids.
The maximum revenue is found by plugging in this value for x into the original revenue function.
R(28) = -2 * (25.75)2 + 103 * 25.75
= 1326.125
~ 1236.16 rounded to the nearest cent
I hope this helps! Please let me know if you have any questions about this, and I will get back to you as soon as I can.