00:00This video is part of a Google Form quiz that teachers can assign to their students for homework.
00:06After the students submit their answers, then they can play a video like this one to see the
00:10answer explained. We've made more than 100 quizzes as Google Forms with free access videos,
00:17which teachers are welcome to copy for free. To get access to these, please see the link in the
00:22description. This video is based on a question from an actual state exam. You may have one like
00:28this on your state exam. If you've already done so, before watching this video, we suggest that you
00:34watch the video on how to calculate perimeters. Isabel divides a rectangle equally into three
00:40smaller rectangles and colors the middle rectangle. What is the perimeter of the colored rectangle?
00:47This is the rectangle that Isabel started with. Its base is 15 inches long. Its height is 9 inches long.
00:54Then she divided this one rectangle equally. The final picture shows us three rectangles. The
01:00center one, which we're calling rectangle B, is colored red. The question asks us,
01:06what's the perimeter of the colored rectangle? To calculate the perimeter, we need to know the
01:11length of each side. The directions say that Isabel divided this big rectangle equally into three
01:17smaller rectangles. That means she divided 9 by 3. 9 divided by 3 equals 3.
01:23So each of these short sides is 3 inches long. We know that for each rectangle, its short sides are
01:29the same length as each other. So the other short side of each of these rectangles is also 3 inches
01:35long. Now we need to know the length of the long sides of the rectangle. Rectangle C has two long sides.
01:43The bottom side is 15 inches based on the question's drawing. This top side must be 15 inches too,
01:48because the long sides of a rectangle are the same length as each other. Rectangle B's bottom side is
01:55the same line as rectangle C's top side. So this side is 15 inches long. Because the long sides of a
02:01given rectangle are the same length, then that means the upper side of rectangle B is also 15 inches long.
02:08Here's a simplified drawing that only shows rectangle B. Let's summarize what we found.
02:13Each of the long sides are 15 inches long. Each of the short sides are 3 inches long.
02:18The perimeter is the total length of all the sides. That's 15, plus 15, plus 3, plus 3.
02:26When we add these up, we get 36 inches.
02:28Let's close. Choice B is correct. Thanks for your attention.
