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### Course: 5th grade>Unit 14

Lesson 5: Converting US Customary units word problems

# Measurement word problem: running laps

Understand how to convert units within the US Customary system to solve word problems. Learn about the importance of having all measurements in the same units to accurately solve problems, and demonstrates how to convert between miles, feet, and yards to determine the solution. Created by Sal Khan and Monterey Institute for Technology and Education.

## Want to join the conversation?

• how much is a furlong and what is a furlong
• Why isn't there a video on the eternal question: "How many fluid ounces will fit into X amount of cups?" because, I'm sorry, I can't figure it out. I've taken the time to understand it for HOURS now and I can't figure it out. It gets to the point where I start to ask questions that are irrelevant to the math, always a great sign: "Why do I need to figure how many fluid ounces fit into how many cups? Why is this relevant? When will I EVER need this skill?" I take the time to carefully read the instructions and the question (and of course, the hints afterwards) with - over the years over trying over and over - a figurative team of scientists behind me and I still can't figure this out. Everytime I think I understand the workings of this small exam created by aliens, the answer I give in is wrong, and it's yet again back to the drawing board, over and over and over AND OVER again.

I'm sorry, but this is getting to the point of stupidity. Or it already got to that point. Can somebody, in plain and simple language, explain to me how much cranberry juice Molly needs? Because, judging by the explanation and this entire concept, I seriously don't think she knows.
• Good question. Let's say Sailor has 32 pints of lemon juice, but Scarlett tried to figure out how many gallons of lemon juice Sailor had to make it easier. Well, we know that 16 pints is a gallon, so technically, 16x2 equals 32. Sailor really has 2 gallons.
• How many yards are there in a meter?
• 0.9144 meters
• While I'm clear with most on the material on the exercises for this part of the unit, I've been having a tough time conceptualizing the "wall" questions. You don't exactly solve them using dimensional analysis (at least when I saw how KA solved it. Please correct me if I'm wrong), so it messes with my brain. For example, a question would go as the following:

"It takes 36 minutes for 7 people to paint 4 walls...How many minutes does it take 9 people to paint 7 seven walls?"

So my mind takes some really messy pathways in an attempt to solve the problem, leading to never ending loop of trial and error. Therefore, could anyone breakdown the process of solving the problem so I could understand how it is solved and why you would solve it that way? Thanks.
• Each person paints walls with a certain speed measured in `(w)alls/(m)inute`. Let's say it is `xw/ym`. And since there are 7 people, we can assume that the overall speed with which walls are getting painted is 7 times that, or `7xw/ym`, And we know that the overall speed was `4 walls/36 minutes`, or `1w/9m`. Now we can set up an equation: `7xw/ym = 1w/9m`. And to figure our what `xw/yw` equals to, we just need to multiply both parts by 1/7. `7xw/ym * 1/7 = 1w/9m * 1/7` = `xw/ym = 1w/63m`. So it takes 63 minutes for 1 person to paint a wall.

Now that you know the speed, you can set up the second equation: `9 * 1w/63m = 7w/xm` = `9w/63m = 7w/xm` = `1w/7m = 7w/xm` *1/7 = `1w/7m * 1/7 = 7w/xm * 1/7` = `1w/49m = 1w/xm`. So, `x = 49`.
• how do you convert square meters back to meters
• That depends on what kind of shape you're talking about.
• What are imperial units?
• Definition of Imperial Units :

A system of weights and measures originally developed in England. Similar but not always the same as US standard units.

Examples of Imperial measures :

Length : inches, feet, yards
Area : square feet, acres
Weight : pounds, ounces,
Volume : fluid ounces, gallons

The Imperial System has been replaced by the Metric System in most countries (including England).
• Where did he get 11 from at - when he said 11*300?
• Sal was doing a rough estimate of 3520 divided by 300. 10 *300 = 3000. 11 * 300 = 3300, and 12*300 = 3600.