Summary
Highlights
This lesson introduces students to finding percentage, rate, or base in problems. Using an example of a bag on sale, it defines percentage as the part or portion of the base, rate as the percent with a percent sign, and base as the original or entire amount often found after the word 'of'.
The video explains that 'of' represents multiplication and 'is' represents an equal sign. It then introduces formulas: Percentage = Rate × Base, Rate = Percentage / Base, and Base = Percentage / Rate. A triangle mnemonic is also provided for easier recall of these formulas.
The first example demonstrates how to find the percentage. Given 'What is 20% of 300?', the video identifies 20% as the rate and 300 as the base. The rate is converted to a decimal (0.20) and then multiplied by the base to get the percentage, which is 60.
The second example focuses on finding the rate: 'What percent of 24 is 12?'. Here, 24 is the base and 12 is the percentage. To find the rate, the percentage (12) is divided by the base (24), resulting in 0.5. This decimal is then converted to a percentage, which is 50%.
The final example illustrates how to find the base: '15 is 20% of what number?'. 20% is identified as the rate and 15 as the percentage. The rate (20%) is converted to a decimal (0.20), and then the percentage (15) is divided by the decimal rate to find the base, which is 75.