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Discovering how to find the value of a single unit when comparing different quantities.
Have you ever stood in a grocery aisle wondering if the giant bag of chips is actually a better deal than the small one, or if it's just a clever marketing trick?
In mathematics, a ratio compares two numbers. But sometimes, comparing ratios like and is confusing. That is where the unit rate comes in! A unit rate is a special ratio where the second quantity is always .
If a carton of eggs costs , what is the unit rate (price per egg)?
$\$0.25$ per egg, or Quick Check
In the unit rate , what is the denominator?
Answer
1
To find a unit rate, you simply perform division. You take the first quantity and divide it by the second quantity. The word 'per' is your signal that you are looking for a unit rate.
Common unit rates include: - Price per ounce (Cost Ounces) - Miles per hour (Distance Time) - Words per minute (Words Minutes)
Sarah typed words in minutes. What is her typing speed in words per minute?
Quick Check
If you buy 4 tickets for $20, what is the unit rate (price per ticket)?
Answer
$5 per ticket
Unit rates are most useful when you need to choose between two options. This is called comparison shopping. By finding the unit rate for both options, you can see which one gives you more for your money. Even if one item has a lower total price, it might actually be more expensive per unit than a larger, higher-priced item.
Which is the better deal?
Option A: ounces of juice for $\$2.5016\
1. Find Unit Rate A: $2.50 \div 10 = \$0.253.20 \div 16 = \ per ounce.
3. Compare: Since $\$0.20 < \, Option B is the better deal!
Which of the following is a unit rate?
If a pack of 5 markers costs $15, what is the unit rate?
To find the unit rate of , you should multiply 100 by 4.
Review Tomorrow
In 24 hours, try to explain to a friend why a 'unit rate' must always have the number 1 in its denominator.
Practice Activity
Next time you are at a store, look at the small print on the price tags. Most stores actually list the 'Unit Price' (like price per ounce) right there for you!