Calculating Area Word Problems – Part 2
SUMMARY KEYWORDS
metres, square metres, area, centimetres, hamster, calculate, buy, hamster cage, yard, covers, fabric, paint, charge, countertop, answer, problem, cage, granite, square feet, wide
Hello Welcome back. The title of this lesson is calculating area word problems. This is part two. And so this will be the second part of when we read these problems pick it apart, try to understand what they’re asking us to do and actually calculate the answer. So first question says joy, bought a piece of fabric that is 30 centimetres long and nine centimetres wide, what is the area of the piece of the fabric? This is what I was saying in the last lesson when you buy fabric from the store, you don’t buy it in terms of how long it is, you buy it by in terms of how much area it covers. So you might buy metre by you might buy fabric by the square metre or something of square centimetres even depending on what the fabric is. So if we have this guy that is 30 centimetres long, then it’s going to be very long and very pretty much narrow, you know something like this, so it said this was 30 centimetres long, and it said it was nine centimetres wide or nine centimetres tall. So what do we have here? We have a situation where we have a rectangle. How do you find the area of this? Well, we have to multiply 30 times nine. I don’t remember what 30 times nine is, but I know how to do it. We lined it up nine times zero, we just write a zero right into there, because nine times 00. We throw away the zero, what is nine times three? Nine times three is 27. That goes right in front and the answer is 270. You can get exactly the same answer by just covering up the zero and saying nine times three is 27. And then just take that zero and tack it right on the end. Now the answer is 270. What it’s centimetres times centimetres and so the unit here is square centimetres, so we put square centimetres 270 Square centimetres. So at the fabric store, they may charge you like you know $1 per square centimetre or whatever and that’s how they’re going to charge you for the fabric. All right, next problem says Derek is going to fence in a yard that is 20 metres long. An eight metres wide, 20 metres long, eight metres wide. What is the area of the yard that he will fence? What is the area of the yard that he will fence? So again, we have a rectangular yard. Let’s draw a quick little picture of what that looks like he said it was 20 metres long and it was eight metres wide, something like this. Of course that’s not a very great rectangle 20 metres long, eight metres wide. So what do we do we multiply these we say what is 20 times eight? Well we say eight times zero is zero, and eight times two from our multiplication tables is 1600 and 60 is the answer. If you want you can just cover up the 08 times two is 16. Throw the zero at the end the answer is 160. And we have metres times metres so it’s square
metres.
Right so when you go to the store, if this was you’re going to fence in a yard that is 20 metres by eight metres. The area the surface area of this yard is 160 square metres. So if I’m going to build a swimming pool that covers the whole area of the yard, they’re going to charge me based on how large the pool is what the area of the pool is. That’s how we get charged. On when things have you know, a, an area to it, we have to calculate the area to know how much to charge. All right, number three, it says Vince needs a piece of granite that’s a countertop that’s made of Rocco granite. Vince needs a piece of granite that is seven feet long and two feet wide for a countertop. What is the area of the piece of granite he needs? It’s exactly the same thing. When you go to a store to purchase countertops, they’re going to charge you by the square by whatever the area is by the square foot or the square centimetre or the square metre, whatever unit they’re measuring. In this case, it’s its feet. So we have this countertop that is seven feet long and only two feet wide, so it’s seven feet long and two feet wide. Alright, and so how do we do this? We say, Well, what is seven times two? Well, from your multiplication table, seven times two is 14. And since it’s feet times feet, the unit of this area is square feet. square feet, 14 square feet. That’s the final answer. So they may charge you, you know, for a very nice piece of granite, they may charge you $100 for a square foot, or $50 for a square foot of granite like that. All right, next problem. It says Lisa is going to paint a wall that is five metres long and three metres tall. What is the area of the wall? She will paint? Why do I need to know the area of the wall? Because when I go to the hardware store and buy paint, when I read the bucket, it’s going to tell me what area that bucket of paint will actually cover. So I’ll know I’ll be able to find out how many buckets of paint I need. That’s the bottom line. So what is this room? It says it’s five metres long. three metres wide. So it’s the room has a five metres long and three metres wide. So how do I find the area of this? Well I just say five times three and from my multiplication tables, I know that five times three is 15 metres times metres, means it’s square metres. So 15 square metres so when I go to the store and I know that my wall is 15 square metres, then I can read the back of the paint cam and I can figure out how many square metres the paint can covers and then I’ll be able to know how many cans I need to buy. Alright, the very last problem we have is it says the base of a hamster cage is 12 centimetres long and eight centimetres wide. What is the area of the base? The base of the hamster cage so we’re told that we have a hamster cage we have our hamster that lives there and it’s 12 centimetres long and eight centimetres wide, something like This eight centimetres wide. How do I find the area of this? Well 12 times eight. And I know from my multiplication tables that 12 times eight is 96. Or you go the other way, eight times 12 is 96. So it’s 96 centimetres. 10. centimetres means square centimetres, so it’s 96 Square centimetres. Why do I care about that? Because when you, you know, when you have a pet like a hamster, you want to make sure to have a cage large enough for that hamster. So depending on the kind of hamster you have, you may need a certain area for the in the bottom of that cage for him to have a happy life. So you want to know the area of the cage to make sure that you’re buying one large enough for that hamster and you can probably go talk to the you know, to the people at the pet store to figure out what area you need in a cage for that hamster that you’re trying to get. So this is doing two purposes we’re trying to calculate area and I’m trying to teach you how to calculate area but also I’m getting you’re trying to think about why we care about area we use area in everything from painting the walls to fertilising the grass in the backyard to pouring concrete for a driveway to purchasing material to make a dress. I mean lots of things we use area for. And so I just want to try to emphasise that to you. So I’d like you to solve all of these problems yourself, make sure you’re getting the right answer. Follow me on to the next lesson. We’re going to change topics just a little bit and begin to talk about the concept of parameter.