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## 3rd grade

### Course: 3rd grade > Unit 10

Lesson 4: Multiply to find area# 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?

- i can't see corectlly, but are those spaces of land the same shape?(6 votes)
- 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.(3 votes)
- 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.(2 votes)

- it totally confused me that video I mean I thought from the scale he drew it that fibbonachi drive was correct(2 votes)
- 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.(3 votes)

- is the area the length times width(0 votes)
- Yes. But only rectangles and squares. LxW is the formula for the squares and rectangles; others, like circles and trapezoids, have different formulas.(2 votes)

- Why do I would have to add all the numbers around the shape but we have to multiply?(0 votes)
- You mean perimeter or area? Area you have to do 4*4 or any multiplication that is shown, and perimeter, you can use a strategy to do it, if it is a square, you can do 4*4 to use a shortcut.(6 votes)

- That reference to pi and the Fibonacci sequence though(2 votes)
- How can I find the area of my land with sides 155,185,125,185 sq fleets(2 votes)
- when u use area u multiply and we u use perimeter u add(2 votes)
- If we add the length and the width of the Apple lane and Fibonacci Drive the answer comes same in both. If we measure the area why does it come different?(2 votes)
- why did you put 40x30=1200 its suppose to be 120(1 vote)
- 4 tens * 3 tens= 12 hundreds because the tens are multiplied as well.(2 votes)

## 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.