Converting between measurement systems
About this video
A mural is 20 yards long, and there are about 10 meters in 11 yards. The video sets up equal ratios, reasons that the length in meters must be less than 20 because meters give a smaller number, and estimates 10/11 of 20 as about 18 meters.
You'll be able to
- set up equal ratios to convert between yards and meters.
- decide whether a converted measurement will be bigger or smaller.
- estimate a conversion using a fraction like 10/11.
Key words
- ratio
- A comparison of two quantities, like 10 meters to 11 yards.
- conversion
- Changing a measurement from one unit to another, like yards to meters.
- yard
- A unit of length in the customary system, a bit shorter than a meter.
- meter
- A unit of length in the metric system.
- approximation
- An answer that is close to the exact value, but not exact.
Transcript
- [Instructor] We're told a mural by Miguel Covarrubias is 20 yards long. It looks like this is the mural right over here. There are approximately 10 meters in 11 yards. Given this ratio about how long is the mural in meters? Pause this video. Have a go at that before we work through this together.
All right, so we're going to compare two things in terms of both meters and yards. And so let's just set up some ratios over here. So there is first the actual mural right over here, it's going to be some number of meters, and we know that number of meters is the same thing as 20 yards, 'cause they give us its length in yards.
And we also know that if I were to have something that is 11 yards long, if I were to measure it in terms of meters, it would be 10 meters. So one way to think about it is we could set, we should say that these ratios need to be equal to each other. Something that 11 yards long is 10 meters, then something that's 20 yards long, well it's going to be some number of meters that relate to 20, the same way that 10 relates to 11.
So the first question I ask you is question mark going to be greater than or less than 20? Well, one way to think about it, if we look on the right side, right over here, however many yards it is, when you measure it in meters, it's a smaller number. So however many yards it is, when you measure it in meters, it's a smaller number.
So first of all, this is going to be less than 20 meters. Now let's try to estimate what that might be. So the measure in meters, and when I look at 10/11 is one way to think about it. That's about a little over 90%. It's like 90, 91%. If I were to take 10 divide it by 11, it's gonna be 0.9 something, 0.90 something I think.
And so if I were to take a similar part of 20, I would get something in the range of a little over 18. So I would say this is going to be approximately 18 meters. I could get a calculator out and calculate this exactly, but this is going to be a pretty good approximation.
Video © Khan Academy, used under CC BY-NC-SA. Watch on Khan Academy. Puzzicle is not affiliated with Khan Academy.