SOLUTION: Find the least amount of material needed to make a square based open box that has a volume of 5000 cubic meters.

Algebra ->  Customizable Word Problem Solvers  -> Evaluation -> SOLUTION: Find the least amount of material needed to make a square based open box that has a volume of 5000 cubic meters.      Log On

Ad: Over 600 Algebra Word Problems at edhelper.com


   



Question 428043: Find the least amount of material needed to make a square based open box that has a volume of 5000 cubic meters.
Answer by htmentor(1343) About Me  (Show Source):
You can put this solution on YOUR website!
The box is open, so it will have 5 sides.
Let a = the side length of the square bottom
Let h = the height of the box
We are given the volume of the box = 5000.
We need to find a formula for the amount of material required for the box.
The bottom will have area a%5E2
Each side will have area ah, and there are 4 of them.
Thus, the total amount of material will be:
M+=+a%5E2+%2B+4ah (1)
The volume of the box, a%5E2h+=+5000
So h+=+5000%2Fa%5E2
Substitute this value for h into equation (1):
M+=+a%5E2+%2B+4a%285000%2Fa%5E2%29+=+a%5E2+%2B+20000%2Fa
To minimize M, we take the derivative and set = 0:
0+=+2a+-+20000%2Fa%5E2
Solve for a:
a%5E3+=+10000+-%3E+a+=+21.544 m
Therefore h+=+5000%2F21.544%5E2+=+10.772 m