John is building a fence around a rectangular pan that is 20 feet long and 16 feet wide. He needs to put a post at each corner and every 4 feet on a side. How many posts are needed?
First, calculate the perimeter of the rectangle.
Perimeter = 2(length) + 2(width)
Perimeter = 2(20) + 2(16)
Perimeter = 40 + 32
Perimeter = 72 feet
Next, divide the perimeter by 4 to find out how many posts are needed on each side.
Number of posts per side = 72 / 4
Number of posts per side = 18 posts
Since there are 4 sides, you can calculate the total number of posts needed by multiplying the number of posts per side by the number of sides.
Total number of posts = 18 posts/side x 4 sides
Total number of posts = 72 posts
Therefore, John will need 72 posts to build the fence around the rectangular pen.