yego.me
💡 Stop wasting time. Read Youtube instead of watch. Download Chrome Extension

Length word problem example


2m read
·Nov 10, 2024

We're told that Pilar has 85 inches of ribbon. She gives her friend Nico 19 inches of ribbon. How much ribbon does Pilar have left? Pause this video and see if you can figure that out.

All right, now let's do it together. So Pilar is starting with 85 inches of ribbon, and I could represent that with what's sometimes known as a tape diagram. I guess we could call it a ribbon diagram in this case.

So let's say the width of this rectangle, or this tape, or this ribbon represents the length of Pilar's ribbon. So this is 85 inches of ribbon right over here. She gives her friend Nico 19 inches of the ribbon. I'll do that in red, so she gives away 19 inches.

So I could think about giving away 19 inches, and this is just, I'm not doing it exactly, but you get a sense of things. So 19 inches might be about that much. So that's 19 inches that Pilar gives away.

So how much ribbon does Pilar have left? Well, it would be this section right over here. Now, how do we figure out how much she has left, this question mark right over here?

Well, there's a couple of ways to think about it. You could say 19 plus the question mark is equal to 85. Let me write that down. 19 plus question mark plus what we're trying to figure out is equal to 85.

So the amount she gave away plus the amount she has left is equal to 85. Or you could say, if I start with 85 and if I were to take away 19, well, that's what I have left.

So you could also say that question mark, the amount that she has left, is equal to 85 minus 19. So what is 85 minus 19? Well, there's a bunch of ways that we can compute it.

One way to do it is I could rewrite 85 as 80 plus 5, essentially separate the tens place from the ones place. We have eight tens, which is the same thing as 80, and then five ones, and then rewrite 19 as 10 and 9.

So if I'm subtracting 19, I'm really subtracting 10 and subtracting 9. Now why is that useful? Well, it's pretty straightforward to say that, all right, 80 minus 10 is going to be equal to 70. Eight tens minus one ten is going to be equal to seven tens.

And so I could rewrite this as 70 plus 5 minus 9. Now, if I just try to figure out what 5 minus 9 is, we get into a little bit of trouble because 9 is bigger than 5.

But what if we were to rewrite 9 in two parts? If we were to say, look, 9 is the same thing as 4 plus 5. So if I'm subtracting 9, that's the same thing as subtracting 5 and then subtracting 4.

And this makes it a little bit easier because we know what that 5 minus 5 is: 0. And so we can rewrite this as 70 minus 4. Now what's that going to be?

Well, we know that 10 minus 4 is equal to 6, so 70 minus 4 is going to be equal to 66. And we're all done. That's how much ribbon she has: 66 inches of ribbon left.

More Articles

View All
2 step estimation word problems
We are told that a race car driver has 28 cars. Each car has four tires. He has to replace all the tires on the cars. He has 22 tires right now. Estimate the total number of tires he needs to buy. So pause this video and see if you can do that. And the ke…
Creative biology at work | High school biology | Khan Academy
[Music] Hi everyone, Salcon here. From finding novel cures for a seemingly incurable disease to diagnosing what’s going on with someone, if you’re a physician or a nurse, you can imagine there’s incredible creativity in biology. And don’t take my word fo…
Dividing a decimal by a whole number on the number line
In this video, we’re going to try to figure out what 0.6, or 6 tenths, divided by 2 is. I’ll give you a little bit of a hint; we have 6 tenths plotted on the number line right over here. One way to think about it is if I wanted to go from zero to six ten…
How Black Climbers Are Closing the Adventure Gap | Podcast | Overheard at National Geographic
Earlier this year, James Edward Mills did something I’ve always wanted to do. He flew to Nepal and directed the base of Mount Everest. I did uh travel with the team, um from Kathmandu to Lukla. Then we basically walked from Lukla to Everest Base Camp. Wow…
Crossing a Snow Packed River | Primal Survivor
The big danger here is I could fall through, and depending on how deep it is, if it’s deep, that river could suck me under the ice. So, I’ve got to come up with a plan. This is where a little bit of, uh, mountaineering strategy comes in. Get my snow shov…
Warren Buffett: How You Need to Be Investing in 2024
If you want the ability to build generational wealth and the financial freedom to retire early and leave the unending corporate rat race, you should be listening to Warren Buffett’s most recent investing advice. For the better part of the last year, lege…