Ratios and measurement | Summary and Q&A

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November 8, 2017
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Khan Academy
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Ratios and measurement

TL;DR

This video explains how to convert units of measure, such as hours to weeks, yards to miles, millimeters to feet, and dollars to ounces, using ratio tables.

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Key Insights

  • 🥳 Ratio tables are useful for converting units of measure by using conversion factors.
  • ⌛ Converting hours to weeks involves multiplying the number of hours by the conversion factor (168 hours per week).
  • 😀 To convert yards to miles, divide the number of yards by the ratio of yards to miles.
  • 🦶 Converting millimeters to feet requires dividing the number of millimeters by the conversion factor (3 feet per yard).

Transcript

  • [Instructor] We're told to complete the ratio table to convert the units of measure from hours to weeks, or weeks to hours. So we see here, they've told us already that there's 168 hours for every one week. One way to think about it is the ratio of hours for every week is 168 to one, and then they calculate, well if we have 1,176 hours, how many ... Read More

Questions & Answers

Q: How can we convert hours to weeks using a ratio table?

To convert hours to weeks using a ratio table, we multiply the number of hours by the conversion factor, which is 168 (hours per week). For example, if we have 1,176 hours, we would multiply it by 7 to get 7 weeks.

Q: What is the process for converting yards to miles using a given ratio?

To convert yards to miles using a given ratio, we need to divide the number of yards by the number of yards per mile. For example, if the ratio is 3,520 yards to 2 miles, we would divide 3,520 by 2 to get 1,760 yards per mile.

Q: How do we convert millimeters to feet using a conversion factor?

To convert millimeters to feet using a conversion factor, we divide the number of millimeters by the conversion factor. For example, if there are 914.4 millimeters in a yard and 3 feet in a yard, we divide 914.4 by 3 to get 304.8 millimeters per foot.

Q: How can we convert dollars per pound to dollars per ounce?

To convert dollars per pound to dollars per ounce, we divide the number of dollars per pound by the number of ounces per pound. For example, if it's $12 per pound of confetti (16 ounces), we divide 12 by 16 to get $0.75 per ounce.

Summary & Key Takeaways

  • The video demonstrates how to use ratio tables to convert units of measure, specifically hours to weeks and vice versa, by multiplying or dividing by a conversion factor.

  • Another example shows how to convert yards to miles using a given ratio, and how to determine the number of yards in a certain number of miles.

  • The video also explains how to convert millimeters to feet by using a conversion factor and simplifying the ratio.

  • Lastly, the video demonstrates converting dollars per pound to dollars per ounce, using division to determine the conversion factor.

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