TEAS 7 Ratios & Proportions: Cross-Multiply Your Way to a Higher Score

By Dr. Priya Sharma, Pharm.D. · Updated April 13, 2026

Student solving ratio and proportion problems for TEAS 7 Math

Every single ratio and proportion question on the TEAS 7 can be solved with one technique: cross-multiplication. Learn it once, and you'll never miss one again.

If fractions are the bread of TEAS Math, ratios and proportions are the butter. They're everywhere — in standalone questions, inside word problems, buried in dosage calculations, and disguised as unit conversions. Students who master this one skill pick up 6-8 "free" questions on every practice test. For the full math breakdown, see our Ultimate TEAS 7 Study Guide.

The beautiful thing about ratios and proportions? Unlike algebra, there's no guesswork. You don't need to "figure out" whether to add, subtract, or use some formula. You set up two fractions, cross-multiply, and divide. That's it. Every. Single. Time. Find out where you currently stand with our free TEAS practice quiz.

💡 Tutor’s Tip: I tell every student: if you're short on study time, learn cross-multiplication FIRST. It applies to ratios, proportions, dosage calculations, metric conversions, and percentage word problems. It's the single highest-ROI math skill on the entire TEAS.

📑 In This Guide

  1. Ratios vs. Proportions
  2. The Cross-Multiplication Method
  3. 5 Ratio/Proportion Disguises
  4. Simplifying Ratios
  5. The 3 Traps That Steal Points
  6. 5-Day Study Plan

Ratios vs. Proportions — What's the Difference?

Before we get into solving, let's clear up the terminology that confuses a lot of students:

A Ratio compares two quantities. It can be written three ways:

  • 3 to 5
  • 3 : 5
  • 3/5

All three mean the exact same thing. The TEAS uses all three formats.

A Proportion says two ratios are equal: 3/5 = 6/10. The TEAS gives you three of the four numbers and asks you to find the missing one.

The Cross-Multiplication Method (Your Only Tool)

Here's the entire technique in four steps. Memorize this and you're done:

🧠 The 4-Step Proportion Solver

  1. Set up two fractions with an = sign between them
  2. Cross-multiply (top-left × bottom-right = bottom-left × top-right)
  3. Solve for X by dividing both sides
  4. Check: Plug your answer back in — do the ratios match?

Worked Example #1 — Basic Proportion

Question: If 3 tablets contain 750 mg, how many milligrams are in 5 tablets?

Step 1 — Set up: 3 tablets / 750 mg = 5 tablets / X mg

Step 2 — Cross-multiply: 3 × X = 750 × 5 → 3X = 3,750

Step 3 — Solve: X = 3,750 ÷ 3 = 1,250 mg

Answer: 1,250 mg

💡 Tutor’s Tip: The most common setup mistake? Mixing up what goes on top vs. bottom. Here's the rule: keep the same labels on the same level. If tablets are on top-left, tablets MUST be on top-right. If mg are on the bottom-left, mg MUST be on the bottom-right. Labels match horizontally — always.

The 5 Ratio/Proportion Disguises on the TEAS

The TEAS rarely says "solve this proportion." Instead, it disguises ratio questions inside real-world scenarios. Here are the five disguises you need to recognize:

Disguise 1: Medication Dosage

Question: A patient needs 400 mg of ibuprofen. Each tablet is 200 mg. How many tablets?

Setup: 1 tablet / 200 mg = X tablets / 400 mg

Cross-multiply: 200X = 400 → X = 2 tablets

(For more complex dosage questions, see our Dosage Calculations guide.)

Disguise 2: Unit Conversion

Question: If 1 inch = 2.54 cm, how many centimeters is 8 inches?

Setup: 1 in / 2.54 cm = 8 in / X cm

Solve: X = 8 × 2.54 = 20.32 cm

Disguise 3: Recipe/Mixture Scaling

Question: A solution requires 3 parts saline to 1 part medication. If you use 12 mL of saline, how much medication?

Setup: 3 parts saline / 1 part med = 12 mL saline / X mL med

Solve: 3X = 12 → X = 4 mL medication

Disguise 4: Map/Scale Problems

Question: On a map, 1 cm = 25 miles. Two cities are 3.5 cm apart. How far are they in real life?

Setup: 1 cm / 25 miles = 3.5 cm / X miles

Solve: X = 3.5 × 25 = 87.5 miles

Disguise 5: Percentage Word Problems

Question: 15% of a class of 240 students got an A. How many students got an A?

Setup: 15 / 100 = X / 240

Solve: 100X = 15 × 240 = 3,600 → X = 36 students

📋 From the Tutor's Desk: I had a student, Marcus, who kept getting every proportion word problem wrong despite knowing how to cross-multiply perfectly. After watching him work through 5 problems, I found the issue: he was reading the question, mentally extracting the numbers, and then setting up his proportion from memory — often swapping the numbers. The fix? I made him physically underline the two pairs of numbers in the question first, then write labels above each one (mg, mL, tablets, etc.) before setting up the fraction. His accuracy went from 40% to 95% in one session. The math wasn't the problem. The reading was.

Simplifying Ratios

The TEAS will sometimes ask you to express a ratio in its simplest form. This is the exact same process as simplifying fractions:

Find the GCF (Greatest Common Factor) of both numbers, then divide both by it.

Example: Simplify 18:24

GCF of 18 and 24 = 6

18 ÷ 6 = 3, 24 ÷ 6 = 4 → 3:4

If you've already mastered Fractions & Decimals, simplifying ratios will feel like second nature — it's the same skill.

The 3 Traps That Steal Your Points

Trap 1: Mismatched Labels
If your left fraction has tablets on top and mg on the bottom, your right fraction MUST follow the same order. Flipping the labels gives you the reciprocal — and a wrong answer.

Trap 2: Not Simplifying
You solve the problem correctly and get 8:12. The answer choices show: A) 8:12 B) 4:6 C) 2:3 D) 3:2. The answer is C — the fully simplified version. Always reduce.

Trap 3: Misreading "Ratio OF part TO whole" vs. "Part TO part"
"The ratio of boys to girls is 3:5" means 3 boys for every 5 girls (part to part). But "the ratio of boys to total students" would be 3:8 (part to whole). The TEAS exploits this distinction ruthlessly.

💡 Tutor’s Tip: Whenever a question says "ratio of X to Y," immediately write it as X/Y. Don't think about it, just write it. Then look for the second pair of numbers to build the other fraction. The moment you have two fractions and an equals sign, you're home free.

Your 5-Day Ratios & Proportions Study Plan

Day Focus Practice
1Cross-multiplication basics + label matching15 basic proportions
2Dosage + unit conversion disguises15 word problems
3Scale, mixture, and percentage disguises15 word problems
4Simplifying ratios + part vs. whole traps15 problems
5Mixed review — all 5 disguises (timed)20 problems in 25 min

What to Study Next

Now that you've got cross-multiplication locked in, these skills build directly on what you've learned:

If you're still setting up proportions incorrectly after practicing, don't spend weeks guessing. A single tutoring session where someone watches your process and catches your specific error is worth more than 50 hours of solo practice with the wrong technique.


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Frequently Asked Questions

What is the difference between a ratio and a proportion?
A ratio compares two quantities (e.g., 3:5 or 3/5). A proportion is an equation stating that two ratios are equal (e.g., 3/5 = 6/10). On the TEAS, you solve proportions by finding the missing value using cross-multiplication.
How many ratio and proportion questions are on the TEAS 7?
Approximately 6-8 of the 38 Math questions directly involve ratios or proportions. However, the same cross-multiplication skill is also needed for dosage calculations, unit conversions, and percentage word problems — making it one of the most broadly useful skills on the test.
What is cross-multiplication?
Cross-multiplication is a method for solving proportions. If a/b = c/d, then a × d = b × c. This converts a fraction equation into a simple multiplication equation that you can solve for the unknown variable.
Are ratio questions on the TEAS 7 hard?
Ratio and proportion questions follow a very predictable pattern. Once you learn to identify the proportion setup and apply cross-multiplication, they become some of the most consistent and reliable points on the test. Most students master the technique within 2-3 practice sessions.
Do I need to simplify ratios on the TEAS?
Yes. The TEAS frequently presents answers in simplified form. If you calculate 12:8, you need to recognize that the simplified answer is 3:2. Always divide both sides by the Greatest Common Factor (GCF) to simplify.

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