Brad is fencing off part of his backyard. He
places 1 post every 3 feet around the perimeter
of a rectangular section measuring 18 feet long
and 15 feet wide. How many posts does Brad
need?



Answer :

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:
[tex]\[ \text{Perimeter} = 2 \times (\text{Length} + \text{Width}) \][/tex]
- Substituting the given dimensions:
[tex]\[ \text{Perimeter} = 2 \times (18 \, \text{feet} + 15 \, \text{feet}) = 2 \times 33 \, \text{feet} = 66 \, \text{feet} \][/tex]

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:
[tex]\[ \frac{\text{Perimeter}}{\text{Distance Between Posts}} = \frac{66 \, \text{feet}}{3 \, \text{feet/post}} = 22 \, \text{posts} \][/tex]

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:
[tex]\[ 22 \, \text{posts} + 1 \, \text{post} = 23 \, \text{posts} \][/tex]

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.