How to write a parabola from a museum admitions question?

Ok, here is the question…. A museum has an admission fee of $14 and averages 300 visitors per day. The museum board decides to raise the fee. Research indicates that for every $1 increase, there would be 10 fewer visitors per day. What admission fee would maximize the revenue?

What im looking for is a complete answer with work written out, i am also wondering how make an equation for a porabola from the information given.

x = amount to raise admission fee
Revenue = (14+x)(300 – 10x) [That's fee times # of visitors]
R = -10x^2 +160x +4200
dR/dx = -20x +160 = 0 [Set dR/dx to 0 to find maximum
-20x = -160
x = 8
So 14+8 = $22 admissin fee maximizes revenue

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3 Responses to How to write a parabola from a museum admitions question?

  1. Mike Robertson says:

    Revenue is the number of tickets sold, 300-10x, times the price per ticket, 14+x.

    So R(x) = (300 -10x) (14 + x)
    References :

  2. ironduke8159 says:

    x = amount to raise admission fee
    Revenue = (14+x)(300 – 10x) [That's fee times # of visitors]
    R = -10x^2 +160x +4200
    dR/dx = -20x +160 = 0 [Set dR/dx to 0 to find maximum
    -20x = -160
    x = 8
    So 14+8 = $22 admissin fee maximizes revenue
    References :

  3. jimschem says:

    Column 1 = dollars per ticket
    Column 2 = people per day
    Column 3 = total dollars taken in

    14 * 300 = 4200 = Starting Point

    15 * 290 = 4350

    16 * 280 = 4480

    17 * 270 = 4590

    Keep going till the total decreases.

    To see the parabola plot dollars per ticket on x-axis
    and total dollars taken in on y-axis.

    This is a problem from calculus called max-min.

    You can solve it without calculs using trial and error.
    References :