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### Unit 1: Lesson 3

Topic C: Unit rates

# Solving unit rate problem

Jayda takes 3 hours to deliver newspapers on her route. What is the rate per hour at which she delivers the newspapers? Created by Sal Khan and Monterey Institute for Technology and Education.

## Want to join the conversation?

• Does anyone understand why Sal had to flip the 3/189 to 189/3 before he did the problem?
• Fractions is basically dividing.

For example 189/3 (improper fraction) = 189/3 <- Divide symbol "/" It's like simplifying it, 189/3 and 3/3 = 63/1. If he flipped it around to 3/189, then it would become smaller (3 hours for every 189 newspapers, or 3 divided by 189), simplified as 1 hour for every 63 newspapers (1 divided by 63), but it would be as decimal form if you divide it (1 divided by 63 and 3 divided by 189, both equals 0.0158730158730159, etc.) = 0.0158730158730159...(irrational number, random numbers forever going on, like pi). But if it was 189/3 (we are dealing with whole numbers) we can turn it into a mixed number: 3 can go in 189 "63" times perfectly, so 63 0/189. So that's how we got our answer. (Or 189 divided by 3, but the other way around. See how 189 divided by 3 (189/3) is different that 3 divided by 189? (3/189) ) Order matters.

I hope that made sense and helped you!
• Is 2:5 the same as 5:2
• The order of the #s matter.
If the problem were (for example) There are 15 kids who have pets in a class. There are 33 kids in the class. What is the ratio of kids who have pets to kids who do not? The answer would be . If you said you would be saying the ratio of kids who do NOT have pets to kids who DO have pets.
• Yes tis has helped me a lot now I will die as a happy man
• wow that doesn't sound good ur not old yet
(1 vote)
• how do i solve a unit rate problem if there are fractions in them? For example, the unit rate of 2/3 cup of sugar for every 1/2 teaspoon of vanilla
• Divide 2/3 and 1/2. Do the same method even if it's a fraction.
• I don't understand these problems...

Fill in the blank with the unit rate:

240 km in 2.5 hours =____ km in 1 hour

Fill in the blank with the unit rate:

\$15 for 4 quarts = \$ for 1 quart

There are 25 computers in a math lab. There are 6 activity booklets for every 2 computers in the math lab. How many activity booklets are in the math lab?

There are activity booklets in the math lab.

You earn \$102 for doing 12 hours of yard work. Your friend earns \$120 working at a store for 15 hours.

How much do you earn for every hour of yard work? \$ per hour

How much does your friend earn each hour at the store? \$ per hour

What would YOU earn for 15 hours worth of yard work (at your hourly rate)? \$ for 15 hours of work
• what helps me is writing the numbers out in a fraction. the first one, how many kms are in one hour if 240 are in 2.5, or 2 and a half, or 2 hrs and thirty minutes. you divide both 2.5 and 240 by 2.5 to get the original ratio.
(1 vote)
• what is unite rate though?
• Unit rates are used to find out how much things happen at a time or ex. rooms per hotel.
• What is the difference between unit rates and price?
• unit rates always have a denominator of one. When prices are expressed as a quantity of one, they are called unit prices. A price is how much you actually pay. The unit price is just per one thing. :)
• What if the numerator is not divisible by the denominator? For example, 42 cupcakes can be made every 30 minutes. How many cupcakes can be made in 1 minute?
• It depends on the question.

Example:
7 leaves fall from the tree every 3 minutes. ABOUT how many leaves will fall from the tree in 1 minute?
You would divide 7 by 3, which equals 2.3333333.... Since the question asks ABOUT how many, you can round it to 2. since 2 times 1 equals 2,then that is your approximate answer.

Hope this helps!