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### Course: Pre-algebra>Unit 3

Lesson 1: Intro to ratios

# Basic ratios

In this video, the instructor explains ratios using three examples: amusement park ride lines, Katie's book collection, and a picture of apples and bananas. Ratios compare two quantities and can be written as "a to b" or "a:b." The video demonstrates how to find and interpret ratios in various situations.

## Want to join the conversation?

• In real life I never used ratios, so my question is are ratios very useful?
• In real life I never used ratios, so my question is are ratios very useful?
• Ratios are very usefull in cooking.
For example, for every 2 cups of flours I need 1 cup of sugar. 2:1 ratio of flour to sugar.
• Do u have videos like this in Spanish my school does math in Spanish and the vocabulary is different making it a lot harder ?
• You can turn on Spanish subtitles.
• what does it really mean when Sal says for every blank there is blank
• it is just different way of say for example 3 to 4 so you could also do 3:4 or for every 3 there is 4. So it i just a different way to specify the problem. there are 3 different ways you can say or write it.
• Can a rate be converted into a ratio, and vice versa?
• Yeah, you can convert ratios into rates and back, although going back is less useful. It is called unit rates. Unit rates, which are a ratio in which the denominator's unit is one, allow us to compare. To calculate unit rates, we simply divide the two numbers in the fraction. The resulting decimal form is the unit rate. Unit prices are a special type of unit rate comparing an item's cost per unit, such as dollars and cents.
• Did you know that you can plot ratios on a coordinate plane? I find that quite interesting!
• I tried to simplify the first question be couldn't.
• The ratio is 11 : 4, since the numbers share no common factors, there is nothing to simplify.
• Are all these examples right?
• Hey ya'll.
Here is the problem:

At a party, the ratio of the number of cheese sandwiches to the number of ham sandwiches is 4:7. The ratio of tuna sandwiches to the number of ham sandwiches is 3:2. What is the ratio of the number of tuna sandwiches to the number of ham sandwiches to the number of cheese sandwiches?

The way I solved it:

T : H : C
7 : 4
3 : 2

But 7 isn't divisible by 2. At least evenly. And you can't have a decimal in a ratio. Should I mark this a typo? Or NEI (Not Enough Info)? Can anyone help me with this please?