An open-top box is to be made from a 12-inch by 24-inch piece of plastic by removing a square from each corner of the plastic and folding up the flaps on each side. What is the maximum possible volume, in cubic inches, of the box?

Respuesta :

Answer:

The maximum possible volume = 332.685 cubic inches

Step-by-step explanation:

From the information given:

Let the height be = x

The length be = 24 - 2x

The width be = 12 - 2x

Then V = x (24 -2x) ( 12 - 2x)

V = x ( 288 -48x - 24x +4x²)

V = x(288 - 72x + 4x²)

V = 288x - 72x² + 4x³

[tex]\dfrac{dV}{dx}= (3x^2 - 36x+ 72)[/tex]

[tex]\implies x^2 - 12x + 24 = 0[/tex]

[tex]=\dfrac{-b \pm \sqrt{b^2 - 4ac}}{2a}[/tex]

[tex]=\dfrac{-(-12) \pm \sqrt{(-12)^2 - 4(1)(24)}}{2(1)}[/tex]

[tex]=\dfrac{12 \pm \sqrt{144 - 96}}{2}[/tex]

[tex]=\dfrac{12 \pm \sqrt{48}}{2}[/tex]

where;

[tex]x \ne \dfrac{12 + \sqrt{48}}{2}[/tex]

∴ [tex]x= \dfrac{12 - \sqrt{48}}{2}[/tex]

x = 2.536 ( since the length cannot be negative)

So, the length x = 24 - 2(2.535) = 18.93

The width = 12 - 2(2.535) = 6.93

heigth = 2.536

V = 18.93 ×  6.93 ×  2.536

V = 332.685 cubic inches

    A box is made from a plastic sheet by removing square from each corner, maximum volume of this box will be 332.55 cubic inches.

Volume of a cuboid:

  •   Volume of a cuboid or rectangular box is given by the expression,

           Volume = Length × Width × Height

Given in the question,

  •    Plastic sheet with length = 12 inches
  •    Width of the sheet = 24 inches
  •    A square has been removed from each corner to fold the box.

Let the measure of each side of a square removed = x inches

Therefore, length of the box = (12 - 2x) inches

Width of the box = (24 - 2x) inches

Height of the box = x inches

Volume of the box (V) = (12 - 2x) × (24 - 2x) × (x)

                                V  =  4x³ - 72x² + 288x

To find the maximum volume of the box differentiate the expression with respect to 'x' and equate it to zero.

V' = 12x² - 144x + 288

For V' = 0,

12x² - 144x + 288 = 0

x² - 12x + 24 = 0

[tex]x=\frac{12\pm\sqrt{(12)^2-4(1)(24)} }{2(1)}[/tex]

[tex]x=(6\pm2\sqrt{3})[/tex]

[tex]x=9.46,2.54[/tex]

For x = 9.46,

Volume of the box = 4(9.46)³- 72(9.46)² + 288

                               = -2769.03 cubic inches

For x = 2.54,

Volume of the box = 4(2.54)³- 72(2.54)² + 288

                               =  332.55 cubic inches

       Therefore, maximum volume of the box will be 332.55 cubic inches.

Learn more about the volume of a cuboid here,

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