Cost per one
Divide price by quantity for each option; the lower unit price is the better deal.
Why it works
$2.50 each beats $3 each.
Ratios · Rates & unit rates · 2.3
Unit price & best buy.
To compare deals, find the unit price (cost per one) of each and choose the smaller. 4 for $12 is $3 each; 6 for $15 is $2.50 each — the second is the better buy.
See it work.
Watch the method
Unit price & best buy
Compare the price per one; the smaller wins.
1
Simplify
Reduce the ratio.
The idea underneath.
From easy to tricky.
Which is the better buy? A: 2 for $10. B: 2 for $6.
1
Answer
B
Which is the better buy? A: 5 for $15. B: 3 for $12.
1
Answer
A
Which is the better buy? A: 2 for $8. B: 6 for $12.
1
Answer
B
Where students slip.
Trap
Comparing totals instead of unit prices.
Fix
Compare cost per ONE item.
Trap
Picking the bigger pack automatically.
Fix
Bigger isn’t always cheaper per unit.
Test yourself.
The Test
12 problems across three tiers. Auto-graded on submit. Hints and a full walkthrough on every question. Your work is saved on this device — sign in to keep it across devices.
0/12Answered
How to answerType just the value. Formatting won't trip you up — we ignore spaces, capital letters, commas, and subscript style, so
t₁ = 5, d = 3 and t1=5,d=3 both count. For a list of numbers, separate them with commas (e.g. 3, 10, 17).Core
Core (4)
C1
Which is the better buy? A: 4 for $8. B: 3 for $12.
Need a hint?
- Find each option’s price per one.
- Choose the lower unit price.
C2
Which is the better buy? A: 5 for $15. B: 3 for $12.
Need a hint?
- Find each option’s price per one.
- Choose the lower unit price.
C3
Which is the better buy? A: 4 for $8. B: 3 for $9.
Need a hint?
- Find each option’s price per one.
- Choose the lower unit price.
C4
Which is the better buy? A: 2 for $4. B: 3 for $9.
Need a hint?
- Find each option’s price per one.
- Choose the lower unit price.
Apply
Apply (4)
A1
Which is the better buy? A: 3 for $12. B: 2 for $6.
Need a hint?
- Find each option’s price per one.
- Choose the lower unit price.
A2
Which is the better buy? A: 2 for $6. B: 4 for $12.
Need a hint?
- Find each option’s price per one.
- Choose the lower unit price.
A3
Which is the better buy? A: 3 for $12. B: 2 for $10.
Need a hint?
- Find each option’s price per one.
- Choose the lower unit price.
A4
Which is the better buy? A: 5 for $10. B: 2 for $8.
Need a hint?
- Find each option’s price per one.
- Choose the lower unit price.
Extension
Extension (4)
E1
Which is the better buy? A: 5 for $10. B: 6 for $30.
Need a hint?
- Find each option’s price per one.
- Choose the lower unit price.
E2
Which is the better buy? A: 4 for $8. B: 4 for $8.
Need a hint?
- Find each option’s price per one.
- Choose the lower unit price.
E3
Which is the better buy? A: 4 for $8. B: 3 for $6.
Need a hint?
- Find each option’s price per one.
- Choose the lower unit price.
E4
Which is the better buy? A: 5 for $10. B: 3 for $6.
Need a hint?
- Find each option’s price per one.
- Choose the lower unit price.