Question

A rectangular storage container with an open top is to have a volume of 10m3. Thelength of its base is twice the width. Material for the base costs $ 10 per square meter.Material for the sides costs $ 6 per square meter. Find the cost of the material for thecheapest such container.

Answer 1

Answer:

$163.54

Step-by-step explanation:

Volume of rectangular container = 10m^3

Length = 2(width)

Material for the base cost $10 per square meter

Material for the side cost $6 per square meter

Volume = L*B*H

L= 2W

V = (2W).W. H

10 = 2W^2.H

H = 10 /2W^2

H = 5/W^2

Let C(w) = cost function

C(w) = 10(L.W) + 6(2.L.H + 2.W.H)

= 10(2W.W) + 6(2.2W.H + 2.W.H)

= 10(2W^2) + 6(4W.H + 2.W.H)

= 10(2W^2) + 6(4W*5/W^2 + 2.W*5/W^2)

= 20W^2 + 6(20/W + 10/W)

= 20W^2 + 6((10+20)/W)

= 20W^2 + 6(30/W)

C(w) = 20W^2 + 180/W

To find the minimum value, differentiate C with respect to w

C'(w) = 40W - 180/W^2

Put C'(w) = 0

0 = 40W - 180/W^2

40W = 180/W^2

40W^3 = 180

W^3 = 180/40

W^3 = 4.5

W = cube rt(4.5)

W = 1.65m

C = 20(1.65)^2 + 180/1.65

C = 54.45 + 109.09

C= $163.54

Minimum cost = $163.54