Unit Price
In short: Unit price is the cost of one single unit of an item, such as one ounce, one pound or one item, found by dividing the total price by the number of units.
6th GradeRatios and Percents6.RP.A.3b
What is Unit Price?
A unit price lets you compare two deals fairly even when the packages differ in size. A big jar and a small jar can only be judged side by side once each is priced for the same amount.
Precisely, for a total cost \(C\) and a quantity \(q > 0\), the unit price is \(\frac{C}{q}\) dollars per unit. The package with the smaller value gives you more for your money.
How to spot it
- A store shelf shows two package sizes with different prices for the same product.
- You are asked which deal is cheaper, or which is the better buy.
- A sign says “$3.60 for 12” and you need the price of one.
- A problem asks for cost per ounce, per pound, per liter or per item.
The method
- Write the total price on top of the quantity, such as \(\frac{\$6.30}{18 \text{ oz}}\).
- Divide the price by the quantity and keep enough decimal places to tell the deals apart.
- Do the same for the other package, using the same unit of measure in both.
- Pick the smaller number as the better buy, and say the unit out loud, such as dollars per ounce.
Unit Price: solved example
Problem
At a farm stand in Vermont, maple syrup comes in an 8-ounce bottle for $5.84 or a 32-ounce jug for $20.80. Which one has the lower price per ounce, and by how much?
Solution
Bottle: \(5.84 \div 8 = 0.73\) dollars per ounce.
Jug: \(20.80 \div 32 = 0.65\) dollars per ounce. The jug is cheaper by \(0.73 – 0.65 = 0.08\), so the jug saves $0.08 per ounce.
Try it
Question 1
A pack of 15 pencils costs $4.20. What is the price of one pencil?
Show the answer
\(4.20 \div 15 = 0.28\), so one pencil costs \$0.28.
Question 2
Brand A sells 2.5 pounds of rice for $4.50 and Brand B sells 4 pounds for $7.40. Which is cheaper per pound?
Show the answer
A: \(4.50 \div 2.5 = 1.80\). B: \(7.40 \div 4 = 1.85\). Brand A is cheaper per pound.
Unit Price vs. Unit Rate
A unit price is always about money: dollars for one item or one measure. A unit rate is the broader idea and can describe miles per hour, words per minute or gallons per second. Every unit price is a unit rate, but not the other way around.
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Whole dictionary: A–Z · 6th Grade · Ratios and Percents