Question

Use Lagrange multipliers to solve the following exercise. A home improvement contractor is painting the walls and ceiling of a rectangular room. The volume of the room is 18042.75 cubic ft. The cost of wall paint is $0.06 per square foot and the cost of ceiling paint is $0.11 per square foot. Find the room dimensions that result in a minimum cost for the paint.

Answer 1

Answer:

Let the width of the garden =x meter

Then length=(x+4) meter

Half perimeter =36 m

So perimeter of garden =(2×36)=72 meters

According to the question

⇒2(l+b)=72

⇒2(x+x+4)=72

⇒2x+2x+4=74⇒4x=64⇒x=16 meters

Hence,the width of the garden =16 meters

The length of the garden =(16+4)=20 meters