1. Applications of Maxima and Minima Optimization Problems
Lecture 13
Applications of Maxima and Minima Optimization Problems
Gymnast Clothing manufactures expensive hockey jerseys for sale to college bookstores in production runs of up to Its cost ($) for a run of x hockey jerseys is
C(x) = x + 0.2x2
How many jerseys should Gymnast produce per production run in order to minimize average cost?

2. Optimization Problems
Identify the unknown(s). Draw and label a diagram as needed.
Identify the objective function. The quantity to be minimized or maximized.
Identify the constraints.
4. State the optimization problem.
5. Eliminate extra variables.
6. Find the absolute maximum (minimum) of the objective function.

3. Optimization
Ex. An open box is formed by cutting identical squares from each corner of a 4 in. by 4 in. sheet of paper. Find the dimensions of the box that will yield the maximum volume. x
4 – 2x x x x
4 – 2x

4. Critical points:
The dimensions are 8/3 in. by 8/3 in. by 2/3 in. giving a maximum box volume of 4.74 in3.

5. Optimization Maximum volume of 4.74 in3 occurs at x = 2/3
The dimensions are 8/3 in. by 8/3 in. by 2/3 in. giving a maximum box volume of 4.74 in3.

6. Example
An metal can with volume 60 in3 is to be constructed in the shape of a right circular cylinder. If the cost of the material for the side is $0.05/in.2 and the cost of the material for the top and bottom is $0.03/in.2 Find the dimensions of the can that will minimize the cost.
top and bottom
cost
side

7. Therefore:
h >0 and r >0 So
Sub. in for h
which yields

8. Graph of cost function to verify absolute minimum:
2.5
So with a radius ≈ 2.52 in. and height ≈ 3.02 in. the cost is minimized at ≈ $3.58.

9. Optimization Problems
Identify the unknown(s). Draw and label a diagram as needed.
Identify the objective function. The quantity to be minimized or maximized.
Identify the constraints.
4. State the optimization problem.
5. Eliminate extra variables.
6. Find the absolute maximum (minimum) of the objective function.

10. Good Fences Make Good Neighbors!! (from Waner pg. 312, problem # 11)
I want to fence in a rectangular vegetable patch. The fencing for the east and west sides costs $4/foot, and the fencing for the north and south sides costs only $2/foot. I have a budget of $80 for the project. What is the largest area I can enclose??