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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.

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  • spunky sam blue style avatar for user Brad Smith
    Does anyone understand why Sal had to flip the 3/189 to 189/3 before he did the problem?
    (290 votes)
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    • sneak peak green style avatar for user Hao
      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!
      (67 votes)
  • leaf red style avatar for user Max
    Is 2:5 the same as 5:2
    (57 votes)
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    • marcimus pink style avatar for user Ninja Gal
      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.
      (21 votes)
  • blobby green style avatar for user 27kimj
    Yes tis has helped me a lot now I will die as a happy man
    (10 votes)
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  • marcimus pink style avatar for user cricket2179
    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
    (6 votes)
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  • blobby green style avatar for user Daniel Brennan
    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
    (8 votes)
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    • piceratops sapling style avatar for user antwon
      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.
      (0 votes)
  • aqualine ultimate style avatar for user liam.dziki
    the ratios are the same with 5 apples and 6 banana too so it is it is still 5.6 or 6.5
    (7 votes)
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  • duskpin seedling style avatar for user nichoasp000
    what is unite rate though?
    (4 votes)
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  • blobby green style avatar for user dania.mubasher007
    What is the difference between unit rates and price?
    (2 votes)
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  • marcimus pink style avatar for user sstoops
    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?
    (3 votes)
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    • marcimus pink style avatar for user A N
      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?
      Answer:
      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!
      (6 votes)
  • blobby green style avatar for user lavanyaand
    You basically divide both by a divisor then simplify.
    -Tell if it helps.
    (5 votes)
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Video transcript

Jayda takes 3 hours to deliver 189 newspapers on her paper route. What is the rate per hour at which she delivers the newspaper? So this first sentence tells us that she delivers, or she takes, 3 hours to deliver 189 newspapers. So you have 3 hours for every 189 newspapers. That's what the first sentence told us. But we want to figure out the rate per hour, or the newspapers per hour, so we can really just flip this rate right here. So if we were to just flip it, we would have 189 newspapers for every 3 hours, which is really the same information. We're just flipping what's in the numerator and what's in the denominator. Now we want to write it in as simple as possible form, and let's see if this top number is divisible by 3. 1 plus 8 is 9, plus 9 is 18. So that is divisible by 3. So let's divide this numerator and this denominator by 3 to simplify things. So if you divide 189 by 3. Let's do it over on the side right here. 3 goes into 189. 3 goes and 18 six times. 6 times 3 is 18. Subtract. Bring down the 9. 18 minus 18 was nothing. 3 goes into 9 exactly three times. 3 times 3 is 9, no remainder. So if you divide 189 by 3, you get 63, and if you divide 3 by 3, you're going to get 1. You have to divide both the numerator and the denominator by the same number. So now we have 63 newspapers for every 1 hour. Or we could write this as 63 over 1 newspapers per hour. Or we could write this as 63, because 63 over 1 is the same thing as 63 newspapers per hour.