Math Problem Statement

Esme has a rectangular garden as shown below. To surround her entire garden, without cutting or bending any pieces of fence, what is the smallest number of pieces of fence that she needs to buy?

Solution

To solve this, we calculate the total perimeter of the garden and determine how many fence pieces are needed based on the available fence sizes.

Step 1: Calculate the perimeter

The garden is rectangular with dimensions:

  • Length = 6m6 \, \text{m}
  • Width = 3m3 \, \text{m}

The perimeter of a rectangle is given by: P=2×(length+width)P = 2 \times (\text{length} + \text{width}) Substituting the values: P=2×(6+3)=2×9=18mP = 2 \times (6 + 3) = 2 \times 9 = 18 \, \text{m}

Step 2: Find the smallest number of pieces

We need a total length of 18 meters, and we cannot cut or bend the fence pieces. The available fence sizes are 0.6m0.6 \, \text{m}, 1.8m1.8 \, \text{m}, and 2.1m2.1 \, \text{m}. We aim to minimize the number of pieces.

Strategy:

  • Use as many large pieces (2.1m2.1 \, \text{m}) as possible.
  • Then use smaller pieces to make up the remainder.

Calculation:

  1. Number of 2.1m2.1 \, \text{m} pieces: Maximum number of 2.1m pieces=182.1=8\text{Maximum number of } 2.1 \, \text{m pieces} = \left\lfloor \frac{18}{2.1} \right\rfloor = 8 Total length from 8 pieces: 8×2.1=16.8m8 \times 2.1 = 16.8 \, \text{m} Remaining length: 1816.8=1.2m18 - 16.8 = 1.2 \, \text{m}

  2. Use 1.8m1.8 \, \text{m} or 0.6m0.6 \, \text{m} pieces for the remaining 1.2m1.2 \, \text{m}:

    • 1.2m1.2 \, \text{m} can be exactly made up with: 2pieces of 0.6m2 \, \text{pieces of } 0.6 \, \text{m}

Total number of pieces:

  • 8pieces of 2.1m8 \, \text{pieces of } 2.1 \, \text{m}
  • 2pieces of 0.6m2 \, \text{pieces of } 0.6 \, \text{m}

Total pieces: 8+2=108 + 2 = 10

Final Answer:

Esme needs 10 pieces of fence to surround her garden.

Let me know if you have any questions or want further details!

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Math Problem Analysis

Mathematical Concepts

Perimeter calculation
Optimization
Division with remainders

Formulas

Perimeter of a rectangle: P = 2 × (length + width)

Theorems

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Suitable Grade Level

Grades 5-7