1강Problem-Solving and Data Analysis무료 체험

Ratios and proportions

강좌: Problem-Solving and Data Analysis
문제 유형: 비율·비례·단위
연습: 전략 강의
언어: 베트남어 · 영어

이 강의는 선택한 언어 버전이 아직 없어 영어 버전을 보여 줍니다.

Terminology

Ratio	A comparison of two quantities by number or size. The ratio of a to b can be written as a:b or a/b. Ex: Bình has 15 apples and 30 oranges. The ratio of apples to oranges is 15:30, or 1:2.
Rate	A special type of ratio that compares two quantities with different units. Ex: Nam's motorbike travels at a speed of 40km/h.
Proportion	An equation stating that two or more ratios are equal; it is often used to find unknown quantities Ex: To make one cake, Thảo needs 2 cups of flour and 1 cup of water. So to make 5 cakes, Thảo needs 10 cups of flour and 5 cups of water.

Percentage	A ratio out of 100 that represents a part-to-whole relationship. Percent (%) means 1/100.
Percent value	The values needed to find a percentage. There are 2 of them: the part and the whole.
Complementary percentages	Two percentages that add up to 100%. Ex: 30%+ 70%= 100%.
Decimal	A way of writing a number using the digits 0 to 9 and a decimal point to show the fractional part. Ex: the number 3.14 is a decimal whose whole-number part is 3 and whose fractional part is 0.14.
Fraction	A way of writing a number as one quantity divided by another. It has two parts: the numerator and the denominator. The numerator is the number above the fraction bar and the denominator is the number below it. The two parts are separated by a slash or a fraction bar. Ex: the fraction 1/2 has numerator 1 and denominator 2.
Discount	A reduction in the price of a product or service. Ex: If a product is listed at $100 and is discounted by 20%, its actual selling price is only $80.
Tip	Extra money paid to service staff in restaurants, eateries, hotels, or other services. Ex: If the tip is 10% and the total bill is 100.000 đồng, then the tip is 10% x 100.000 đồng = 10.000 đồng.
Commission rate	The percentage of a transaction or sale that is paid to the person or company that completed it. Ex: A salesperson earns a 5% commission rate on the total value of the products sold. If the total value sold is 100 million đồng, the commission is 5% x 100 million đồng = 5 million đồng.

Formulas

A ratio is a comparison of two quantities. The ratio of a to b can be written as a : b or or a to b.

Example: Pepper has 3 hats and 2 scarves ⇒ The ratio of hats to scarves is 3 to 2 or

Two types: part-to-part ratios and part-to-whole ratios.

Example: A basket holds 5 blue balls and 3 red balls

Part-to-part ratio: The ratio of blue balls to red balls is
Part-to-whole ratio: The ratio of blue balls to all the balls is

A proportion is an equation stating that two ratios are equal. Proportions help us find equivalent ratios and solve for unknown quantities.

Example: A recipe calls for 3 cups of flour for every cup of water. We want to use 6 cups of flour. To find how much water we need, we set up a proportion: