Lesson 3.2Comparing Unit Prices (Best Buy)
Start hereWords, worked example, and sentence starters
Learning target 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.
Start hereWords for this lesson
Read each word before you begin. Say it out loud.
| Word | What it means | Example |
|---|---|---|
| Rates and Unit RatesSpanish: Tasas y tasas unitarias | A rate compares different units; a unit rate compares a quantity to 1 unit. | 180 miles in 3 hours = 60 miles per 1 hour. |
| RateSpanish: Tasa | A ratio comparing two amounts with different units, like miles per hour. | $12 for 4 games is a rate |
| Unit RateSpanish: Tasa unitaria | A rate for just 1 of something, like cost for 1 item. | $3 per 1 game |
| PerSpanish: Por | For each one. Example: 5 dollars per book. | 60 miles per hour means 60 miles for every 1 hour |
| RatioSpanish: Razón | A way to compare two amounts, like 3 to 2. | 5 to 3 or 5:3 |
| Unit priceSpanish: Precio unitario | A unit rate that gives the cost of exactly 1 item, like $0.60 per game. | $1.75 per pound |
How it worksWorked exampledeciding which package is the better buy
These numbers are not on your problems. The steps are. Follow them with your own numbers.
Bag A holds 4 lb for $7.00. Bag B holds 6 lb for $9.60. Which is the better buy?
- Find the unit price of A. $7.00 ÷ 4 = $1.75 per pound
- Find the unit price of B. $9.60 ÷ 6 = $1.60 per pound
- Compare the two unit prices. $1.60 is LESS than $1.75
- Name the better buy — the lower price per pound wins.
Answer: Bag B is the better buy at $1.60 per pound.
Now you trySame steps, your turn
The steps are the same as the worked example. The numbers are yours. Do the work.
Bag C holds 3 lb for $5.55. Bag D holds 5 lb for $8.75. Which is the better buy?
- Unit price of C. $5.55 ÷ = $ per pound
- Unit price of D. $8.75 ÷ = $ per pound
- Compare. $ is than $
- The better buy is Bag .
Say it and write itSentence starters
Finish each sentence out loud with a partner. Then use them in your writing.
- The unit price of is per .
- is the better buy because .
- You cannot compare the total prices because .
- The savings per is .
Word bank unit pricebetter buycomparetotaldividelowerhigherless thangreater thanpersaveeach
Watch outA common mistake
A common mistake in Rates and Unit Rates is comparing total costs instead of unit rates: a student sees Pack X at $4.00 for 10 tokens and Pack Y at $6.00 for 16 tokens and picks Pack X just because $4.00 is the smaller number, without dividing to find the cost per token ($0.40 for Pack X vs. $0.375 for Pack Y — Pack Y is actually the better buy). A second common mistake is dividing backwards — finding tokens ÷ cost instead of cost ÷ tokens — which turns 'dollars per token' into 'tokens per dollar' and gives an answer that looks reasonable but answers the wrong question. Always divide the total cost by the number of items, and check that your unit rate answers 'the cost for ONE item,' not the reverse.
Lesson 3.2Comparing Unit Prices (Best Buy)
Apply Day · Version ASupported practice
Learning target 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.
-
1Complete each step, then write the final answer.
A booth charges $12 for 4 games. What is the cost for 1 game?
Show your workHint Divide the cost by the number of games.
Final answer: -
2Complete each step, then write the final answer.
A pack of 4 stickers costs $1. What is the cost for 1 sticker?
Show your workHint Divide the cost by the number of stickers.
Final answer: -
3Complete each step, then write the final answer.
Kim walks 6 miles in 2 hours. She walks at the same speed. How many miles does she walk per hour?
Show your workHint Divide the miles by the hours.
Final answer:
Lesson 3.2Comparing Unit Prices (Best Buy)
Apply Day · Version BCore practice
Learning target 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.
-
1Circle the letter of the best answer. Show how you know.
Compare both booths at 10 games. Booth A charges $4 for 5 games. Booth B charges $6 for 10 games. Which booth is the better buy?
- ABooth B — $0.60 per game
- BBooth A — $0.80 per game
- CBooth A — it costs less in all
- DThey cost the same per game
Show your work -
2Complete each step, then write the final answer.
A cyclist rides 36 miles in 3 hours at the same speed. How many miles does she ride per hour?
Show your workFinal answer: -
3Complete each step, then write the final answer.
A booth charges $7 for 4 games. What is the cost for 1 game?
Show your workFinal answer:
Lesson 3.2Comparing Unit Prices (Best Buy)
Apply Day · ChallengeExtension
Learning target 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.
-
1Circle the letter of the best answer. Show how you know.
Booth A charges $3 for 5 games. What is the unit rate in dollars per game?
- A$0.30 per game
- B$0.60 per game
- C$1.67 per game
- D$15.00 per game
per 1 -
2Circle the letter of the best answer. Show how you know.
Booth X charges $8 for 10 games. Booth Y charges $10 for 16 games. Mo says Booth X is the better buy because $8 is less than $10. Which booth is the better buy?
- ABooth Y — $0.625 per game
- BBooth X — $0.80 per game
- CBooth X — it costs less in all
Show your work -
3Complete each step, then write the final answer.
A plane flies 1,500 miles in 3 hours. It keeps the same speed. How many hours does it take to fly 2,500 miles?
Show your workFinal answer: