To determine how many posts Brad needs to fence off a rectangular section of his backyard, follow these steps:
1. Understand the Dimensions:
- The length of the rectangular section is 18 feet.
- The width of the rectangular section is 15 feet.
2. Calculate the Perimeter:
- The perimeter of a rectangle is given by the formula:
\(\[
\text{Perimeter} = 2 \times (\text{Length} + \text{Width})
\]\)
- Substituting the given dimensions:
\(\[
\text{Perimeter} = 2 \times (18 \, \text{feet} + 15 \, \text{feet}) = 2 \times 33 \, \text{feet} = 66 \, \text{feet}
\]\)
3. Determine the Number of Posts:
- Brad places 1 post every 3 feet along the perimeter.
- To find the required number of posts, divide the perimeter by the distance between the posts:
\(\[
\frac{\text{Perimeter}}{\text{Distance Between Posts}} = \frac{66 \, \text{feet}}{3 \, \text{feet/post}} = 22 \, \text{posts}
\]\)
4. Include the Starting Post:
- One additional post is needed at the starting point to complete the enclosure.
- Therefore, add 1 to the total number of posts:
\(\[
22 \, \text{posts} + 1 \, \text{post} = 23 \, \text{posts}
\]\)
5. Conclusion:
- Brad needs a total of 23 posts to completely fence off the rectangular section.
So, Brad needs 23 posts to fence off the section of his backyard.
