Ratio and Proportion: Proportions In the Use of Map Scales
This clip presents a problem involving the scale on a road map comparing inches to miles. The clip explains that checking the answer to see that it makes sense is especially important in proportion problems, because "
when the answer is wrong, it's...
Ratio and Proportion: Solving Word Problems Involving Proportions
This clip presents two word problems involving proportions which require dividing both sides of an equation by the same number. The answers are checked by forming cross products which are equal.
The Meaning of Percentage: Summary: The Meaning of Percentage
This clip summarizes the key points about percentage, stressing at the outset that it's practical to be able to view all fractions with the same denominator. The clip then talks about the different ways we can express the same value in decimal, frac...
Ratio and Proportion: Summary: Ratio and Proportion
This clip summarizes the key points pertaining to ratio and proportion. It explains that a ratio is a kind of fraction used to describe the relative sizes of two numbers, also noting that a proportion is a statement that two ratios are equal. The cl...
The Meaning of Percentage: Changing Fractions to Percents and Percents to Fractions
This clip explains that the easiest way to understand percent is to think of it as a proportion. The clip notes that this allows us to change fractions to decimals, and provides examples of how this is done. The clip then reverses the process and ex...
Ratio and Proportion: Defining Ratio and Proportion
This clip provides definitions and example of the words "ratio" and "proportion." The clip explains that we will be using the word ratio "
as a way of describing the relative sizes of two numbers." The clip also says that in mathematics, a proporti...
Percent in Word Problems: Applying Common Sense
This clip stresses the importance of using common sense to determine if an answer is correct. "Usually, when you set up the proportion wrong," the clip explains, "the answer comes out really impossible
you know right away you've made a mistake."
Percent in Word Problems: Practical Problems Involving Percent and Proportion
This clip establishes that percent means comparing something to 100, then presents a number of practical problems about percentage that are solved by setting up proportions and cross-multiplying.
Percent in Word Problems: Summary: Percent in Word Problems
This clip summarizes the material presented in the lesson on percent in word problems. It touches on several of the key terms and concepts, including proportions and cross-multiplying. It also mentions some of the special words that come up in busin...
Percent in Word Problems: Reviewing Proportion
This clip reiterates that proportion is the key idea in all work with percent. The clip notes that while there may be quicker ways to handle a percent problem, we can always get started with this type of problem by setting up a proportion because, "...