Posted by **Jeff** on Saturday, July 30, 2011 at 11:08am.

7. A cardboard box manufacturer wishes to make open boxes from rectangular pieces of cardboard with dimensions 40 cm by 60 cm by cutting equal squares from the four corners and turning up the sides. Find the length of the side of the cut-out square so that the box has the largest possible volume. Also, find the volume of the box.

- calculus -
**Reiny**, Saturday, July 30, 2011 at 12:28pm
let each side of the cut-outs be x cm

So the base is 60-2x by 40-2x and the height is x

Volume = x(60-2x)(40-2x)

= 4x^3 - 200x^2 + 2400x

d(volume)/dx = 12x^2 - 400x + 2400

= 0 for a max of volume

3x^2 - 100x + 600 = 0 ----- I divided by 4

x = (100 ± √(2800)/6

= 25.5 or 7.85

but clearly 0 < x < 20 or else the sides make no sense.

so the cut-outs should be 7.85 by 7.85 cm

Plug 7.85 into my volume expression to get the max volume

- calculus -
**Jeff**, Sunday, July 31, 2011 at 7:27am
6. A right circular cylinder is to be designed to hold 750 cm3 of processed milk, and to use a minimal amount of material in its construction. Find the dimensions for the container.

- calculus -
**Jeff**, Sunday, July 31, 2011 at 7:27am
A right circular cylinder is to be designed to hold 750 cm3 of processed milk, and to use a minimal amount of material in its construction. Find the dimensions for the container.

- calculus -
**Jed**, Tuesday, August 9, 2011 at 8:53am
If you had a device that could record the Earth's population continuously, would you expect the graph of population versus time to be a continuous ( unbroken) curve? Explain what might cause breaks in the curve.

I'm confused. Thanks in advance for any help.

- calculus -
**Jenny**, Monday, April 30, 2012 at 11:57pm
Tony has a rectangular piece of cardboard which is 60 cm by 40 cm. By cutting squares from each corner of the cardboard and turning up the sides, can he form an open-topped box which will hold (a) 6656 cubic centimeter? (b) 9000 cubic centimeters? (c) what is the maximum amount of space he can obtain?

## Answer this Question

## Related Questions

- math - A cardboard box manufacturer wishes to make open boxes from rectangular ...
- Math - A cardboard manufacturer wishes to make open boxes from square pieces of ...
- Calc - A cardboard box manufacturer makes open boxes from rectangular pieces of ...
- Calculus - an open box is made by cutting out squares from the corners of a ...
- Calculus - A box with an open top is to be made from a square piece of cardboard...
- algebra 2 - you can make an open box from a piece of flat cardboard. First cut ...
- Calculus - A square sheet of cardboard with a side 16 inches is used to make an ...
- Calc - You want to make a rectangular box, open at the top, by cutting the same ...
- calculus - An open box is to be made out of a 8-inch by 14-inch piece of ...
- math - a rectangular sheet of cardboard 4m by 2m is used to make an open box by ...

More Related Questions