Stuck? Start here. Read the steps, try the problem, then check your answer.
I can…
I can describe a rate using its two different units and use a model to find a travel time, and I can find a unit rate to compare prices and decide the better buy.
Key words
Rates and Unit Rates — A rate compares different units; a unit rate compares a quantity to 1 unit.
Rate — A ratio comparing two amounts with different units, like miles per hour.
Unit Rate — A rate for just 1 of something, like cost for 1 item.
Per — For each one. Example: 5 dollars per book.
Ratio — A way to compare two amounts, like 3 to 2.
Unit price — A unit rate that gives the cost of exactly 1 item, like $0.60 per game.
Better Buy — The choice that costs less for each item.
Divide — Splitting a total into equal groups.
Constant — A speed, price, or rate that stays the same.
Total price — What the whole package costs, not the cost of one item.
Steps
Booth A charges $3 for 5 games. I want the cost for just 1 game.
I divide the cost by the games: $3 ÷ 5 = $0.60.
So Booth A costs $0.60 per game. That is the unit rate.
Because this unit rate is money for one item, it has its own name: it is the unit price.
Now I can compare this booth's unit price fairly with any other booth's.
Try it
A snack stand sells 4 juice boxes for $3.00 or 6 juice boxes for $4.20. Which deal is the better buy?
Check your answer
6 for $4.20 — $0.70 each
$3.00 ÷ 4 = $0.75 per juice box. $4.20 ÷ 6 = $0.70 per juice box. $0.70 < $0.75, so 6 for $4.20 is the better buy.
Sentence starter
I know ___ because ___.
Goal: I can explain a rate like "150 miles per hour" using distance and time units, and explain my choice using the words rate, unit rate, per, and better buy.