SOLUTION: An aquarium with a square base has no top. There is a metal frame. Glass costs 10 dollars/m^2 and the frame costs 10 dollars/m. The volume is to be 20 m^3. Express the total cost C

Algebra ->  Customizable Word Problem Solvers  -> Geometry -> SOLUTION: An aquarium with a square base has no top. There is a metal frame. Glass costs 10 dollars/m^2 and the frame costs 10 dollars/m. The volume is to be 20 m^3. Express the total cost C      Log On

Ad: Over 600 Algebra Word Problems at edhelper.com


   



Question 1097462: An aquarium with a square base has no top. There is a metal frame. Glass costs 10 dollars/m^2 and the frame costs 10 dollars/m. The volume is to be 20 m^3. Express the total cost C in terms of the height h in meters. (Hint: work out the cost of the glass and frame separately.)

I/m stuck on this problem! Please help.

Found 2 solutions by josmiceli, greenestamps:
Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
Let +s+ = the side of the square base
The height is +h+ m
+20+=+h%2As+
+s+=+20%2Fh+
--------------------
The cost of the glass is:
+10%2A%28+20%2Fh+%29+%2B+10%2A4%2Ah%2A%2820%2Fh%29+
+200%2Fh+%2B+800+
--------------------
The cost of the frame is:
+10%2A4%2A%28+20%2Fh+%29+%2B+10%2A4%2A%28+20%2Fh+%29+
+800%2Fh+%2B+800%2Fh+
+1600%2Fh+
------------------
+C+=+200%2Fh+%2B+800+%2B+1600%2Fh+
+C+=+1800%2Fh+%2B+800+
Chck the math and get another opinion if needed


Answer by greenestamps(13200) About Me  (Show Source):
You can put this solution on YOUR website!

The first solution is not right....

The aquarium has a square base of side length s and a height of h. The volume is to be 20, so
s%5E2h+=+20
s%5E2+=+20%2Fh
s+=+sqrt%2820%2Fh%29

The glass required is for the base, area s^2, and four sides, each area s*h. That total area is
s%5E2+%2B+4sh+=+20%2Fh+%2B+4h%2Asqrt%2820%2Fh%29
The cost of the glass is then
10%2820%2Fh+%2B+4h%2Asqrt%2820%2Fh%29%29

The metal needed for the frame is 4 sides on top and 4 sides on bottom, each length s, and 4 vertical edges, each length h. The total length of all the edges is
8s+%2B+4h+=+8%2Asqrt%2820%2Fh%29%2B4h
and then the cost for the metal for the frame is
10%288%2Asqrt%2820%2Fh%29%2B4h%29

Then an expression for the total cost in terms of the height h is

10%2820%2Fh+%2B+4h%2Asqrt%2820%2Fh%29+%2B+8%2Asqrt%2820%2Fh%29%2B4h%29