Math Problem Statement

A rancher is planning to build a rectangular fence around his property, with one side of the property being next to a cliff. The property is 6150 square yards, and only the three sides not adjacent to the cliff will be fenced off.

What is the least amount of fencing required for this job?

Solution

Let xx represent the width of the rectangular fenced area (the side perpendicular to the cliff), and let yy represent the length (parallel to the cliff). Since the area of the fenced region is given as 6150 square yards, we have:

xy=6150x \cdot y = 6150

The fencing will cover the two widths and one length (only three sides), so the total length of fencing needed, FF, is:

F=2x+yF = 2x + y

Our goal is to minimize FF, given the constraint xy=6150x \cdot y = 6150. To solve this, we can express yy in terms of xx using the area equation:

y=6150xy = \frac{6150}{x}

Substitute this expression for yy in the fencing equation:

F=2x+6150xF = 2x + \frac{6150}{x}

Now, we have a function of xx alone:

F(x)=2x+6150xF(x) = 2x + \frac{6150}{x}

To find the minimum fencing required, we’ll take the derivative of F(x)F(x) with respect to xx, set it equal to zero, and solve for xx.

  1. Differentiate F(x)F(x) with respect to xx:

    F(x)=26150x2F'(x) = 2 - \frac{6150}{x^2}

  2. Set the derivative equal to zero to find critical points:

    26150x2=02 - \frac{6150}{x^2} = 0

    Rearrange to solve for xx:

    6150x2=2\frac{6150}{x^2} = 2

    x2=61502=3075x^2 = \frac{6150}{2} = 3075

    x=307555.46x = \sqrt{3075} \approx 55.46

  3. Find yy using y=6150xy = \frac{6150}{x}:

    y=615055.46110.92y = \frac{6150}{55.46} \approx 110.92

  4. Calculate the minimum fencing FF:

    F=2x+y=2(55.46)+110.92=110.92+110.92=221.84F = 2x + y = 2(55.46) + 110.92 = 110.92 + 110.92 = 221.84

Thus, the least amount of fencing required is approximately 221.84 yards.

Would you like further details or have any questions?


Follow-up Questions:

  1. How would the solution change if all four sides were fenced?
  2. What if the area was increased to 10,000 square yards?
  3. How does this optimization apply in a real-world ranch setting?
  4. Could we solve this problem using different variables for width and length?
  5. How does calculus help in optimizing resource use in general?

Tip: Optimization problems often benefit from identifying constraints first and expressing all variables in terms of one another to simplify.

Ask a new question for Free

By Image

Drop file here or Click Here to upload

Math Problem Analysis

Mathematical Concepts

Calculus
Optimization
Algebra

Formulas

Area formula: x * y = 6150
Fencing formula: F = 2x + y
Expression for y: y = 6150 / x
Derivative: F'(x) = 2 - 6150 / x^2

Theorems

Optimization using calculus

Suitable Grade Level

Grades 11-12