Can you please elaborate a bit more on the highlighted part for better understanding ?
Bunuel
A laptop company is choosing which components they want to put into their next model. This model laptop will sell for $2000, and every additional component will bring the selling price up an additional $200. However, the company predicts that each time they increase the price, the number of sales will drop by around 5% from the base prediction. What is the best number of components to upgrade in order to maximize revenue?
(A) Six
(B) Five
(C) Four
(D) Three
(E) Two
Are You Up For the Challenge: 700 Level Questions
Base Revenue = 2000 * No of people who buy (say P)
At every step, the per person revenue increases by 10% while the number of people reduce by only 5%. So obviously, it makes sense to carry out some of these steps to increase total revenue. The total revenue will be maximum for a certain number of steps, say n.
Revenue after n steps = 2000 * (
1+.1n) * p * (1 - .05n)To maximize revenue, we need (1+.1n) * (1 - .05n) to take its maximum value.
\((1+.1n) * (1 - .05n) = 1 + .05n - .005n^2 \)
This is a quadratic which is downward opening parabola (because a is negative) and its maximum value will be obtained at n = -b/2a
So n = .05/.01 = 5
Answer (B)Note that even at n = 6 or 7, the revenue obtained will be higher than base revenue but it will be lower than the revenue obtained at n = 5.
Here is a video discussing the parabola form of quadratics:
https://youtu.be/QOSVZ7JLuH0