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### Course: 3rd grade (Eureka Math/EngageNY)>Unit 4

Lesson 4: Topic D: Applications of area using side lengths of figures

# Comparing areas of plots of land

Sal finds area of two rectangles to solve a word problem. Created by Sal Khan.

## Want to join the conversation?

• This video totally confused me. I mean I thought from the scale he drew that Fibbonachi Drive was correct?
• To look at the drawings is to estimate the size of something. You need to calculate the exact area using the numbers provided to work out which one is bigger.

I hope this helps.
• Is there a trick for telling when you are doing area or perimeter? If so, what is this trick? I would really like to know. I'm guessing there are multiple.
• That's a hard question to answer...but take in mind that perimeter is the outside of a 2-D shape will area is the land or whatever that it covers. For example a square fence with the dimensions of 12 ft by 12 ft. You can multiply and find out how many ft^2 can fit inside the fence or you can see how much you need to make the outside edges or fences.
(1 vote)
• what are the square meters?
• Square meters are meters raised to the power of 2 (m^2). When calculating areas, your unit will always end up squared because you are multiplying a side by a side, or unit by unit. Think of it this way, if you are multiplying 2 x 2 you can simplify that to 2^2 or 2 squared; same goes for meters and other units.
• looking for fun welcome to the cup head show!
• how many measurements are there?
• There are many measurements. However, they are not really important unless you have different measurements. Then you have to do more math to find area.
• Hi, umm. Which side is the length and which side is the width?
I've noticed in the exams the "length" and "width" switch sides frequently yet my answers always seem to be wrong. Is there a set law as to what side is the length and which one is the width?
(1 vote)
• It doesn't really matter unless the question asks you to determine the length and the width. The width is determined wide it is the length is determined how long it is. Normally, the length is longer than the width.
(1 vote)
• Is the number for the plot on apple lane the first 6 numbers for pi? Also, is the one on Fibonacci Drive really digits in Fibonacci?
(1 vote)
• hehe, yep that's true. Well noticed!
(1 vote)
• why do most peolpe love mickey mouse?

## Video transcript

Diya is looking to buy a plot of land to build her home on. She finally narrows her search to two plots that both have good locations. The plot at 314159 Apple Lane has a width of 30 meters and a length of 40 meters. The plot at 11235 Fibonacci Drive has a width of 50 meters and a length of 20 meters. They are each being sold for \$36,000. Which one is a better deal? So they're the same price, and they're in comparable neighborhoods. So really, the better deal is the one that actually gets me more area. So I encourage you to pause the video and think about, which one of these am I getting more land for the same amount of money? Well, to think about how much land I'm getting, I'm really thinking about, how much space is that plot taking up? Or I'm really thinking about, what is the area of each of these plots? And we've already figured out that you can calculate the area of a rectangle by multiplying its length times its width. So the area of Apple Lane is 40 meters times 30 meters, which is equal to-- 40 times 3 is 120. 40 times 30 is 1,200. And then it's meters times meters. Or you can view this as square meters, 1,200 square meters. Now let's think about what the area of the plot at Fibonacci Drive is. So its length is 20. Its width is 50. So here the area is 20 meters times 50 meters, which is equal to-- 20 times 5 is 100. 20 times 50 is 1,000 square meters. So it's pretty clear when you calculate the area that Apple Lane, you're getting more square meters than you would get at Fibonacci Drive. And literally, when we say 1,200 square meters, that means if you were to put a 1 meter by 1 meter square here-- so a really small one like that-- then you could fit 1,200 of these on this plot of land, while you could only fit 1,000 of them on this plot of land-- of these 1 meter by 1 meter squares. So we have a larger area, same neighborhood or comparable neighborhood for the same price. I would go with Apple Lane being the better deal.