SAT Math skill page
Use ratios, unit rates, and proportions to solve SAT word problems without losing track of the parts.
What this tests
Practice examples
The ratio of red beads to blue beads is 3:5. If there are 40 beads total, how many are blue?
Answer: 25
There are 3 + 5 = 8 total ratio parts. Each part is 40 / 8 = 5 beads. Blue beads are 5 parts, so 5(5) = 25.
On a map, 2 inches represents 15 miles. How many miles are represented by 6 inches?
Answer: 45
Six inches is 3 times 2 inches, so the distance is 3 times 15 miles, or 45 miles.
A snack mix has almonds and cashews in a ratio of 4:3. If the mix contains 18 cashews, how many total nuts are in the mix?
Answer: 42
Cashews represent 3 parts. If 3 parts equals 18, then 1 part equals 6. The total ratio has 7 parts, so the mix has 7(6) = 42 nuts.
Avoid these traps
In a ratio like 3:5, the whole is 8 parts, not 5 parts.
Read whether the question asks for one group, another group, or the total.
When a proportion changes, every related quantity must scale by the same factor.
Study plan
Related practice
FAQ
A ratio compares quantities. A proportion says two ratios are equal and lets you scale from one situation to another.
Ratios connect to rates, scale drawings, mixtures, data tables, and many real-world word problems.
Students often treat one side of the ratio as the whole instead of adding all parts to find the total.
