Thread: Rectangular box

A rectangular box is to be made from a rectangular piece of shee metal 20in wide and 30in long by cutting a square piece of equal size from each of the corners and bending up the sides so that they make a 90 degree angle with the base. The base of the finished box will be 200 square inches. About how many inches high will the box be?

Originally Posted by sarahh

A rectangular box is to be made from a rectangular piece of shee metal 20in wide and 30in long by cutting a square piece of equal size from each of the corners and bending up the sides so that they make a 90 degree angle with the base. The base of the finished box will be 200 square inches. About how many inches high will the box be?

Let x be the length of one side of one of the squares you have to cut off.

Then you get:

......... Expand the brackets. You'll get aquadratic equation:

......... Solve this equation for x. Only one of the two solutions is valid with your problem.

(For confirmation only: x = 5)

Why do we reject the 20 answer again?

Originally Posted by sarahh

Why do we reject the 20 answer again?

Plug in the solution into the original equation:



That means you cut off more than there exists. In my opinion quite impossible but the modern science ...

Ahh that does make sense. Many thanks earboth!
Sarah H.