Question

A rectangular storage container with an open top is to have a volume of 10 m3. The length of this base is twice the width. Material for the base costs $20 per square meter. Material for the sides costs $12 per square meter.

Answer 1

$ 327.08

Explanation:

Let x = width of the container,

Then Length of the container = 2x

Let h = height of the container,

volume of the container can be calculated as length × width × height

= 2x × x × h

= 2x² h

Then we can say Volume =

= 2x² h=10

If we simplify inorder to get h

We have h= 5/x²

Then the area= (2L×h) +(2xh)

Where L is lenght

x= wish

h= height

= 2× 2x × h+ x× h

= 4x× 5/x + 2x × 5/x

Area = 30/x

Now, the area of the base = length × width

But from question, for the base costs $20 per square meter. Material for the sides costs $12 per square meter

Then the cost C(x)= 2x²× 20+30/x ×12

C(x)= 40x²+35/x²

If we differenciate wrt x we have

C(x)= 80-360/x²

If we equate C(x)=0the

80=360/x²

x= 1.651

If substitute to C(x)= 40x²+35/x²

C(x) = 40(1.651)² + 35/(1.651)²

We have cost= 327.08