Module · Arithmetic & Number Properties
Chapter 7: Ratios & Proportions
Arithmetic
4 topics
🎯 1 practice questions
What this chapter covers
The 4 topics below make up Ratios & Proportions on the GRE. Click any topic to open its notes, examples and practice test.
Study material & tests
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Formula Reference Sheet
This chapter
Ratio basics
| Ratio as a fraction | a : b = a/b (same information) |
|---|---|
| Scaling a ratio | a : b = ka : kb for any k ≠ 0 |
| Dividing a total in a : b | shares = [a/(a+b)] × T and [b/(a+b)] × T |
| Combining a : b and b : c | make the shared term equal, then read a : b : c |
Proportion & variation
| Proportion (cross-multiply) | a/b = c/d ⇔ a·d = b·c |
|---|---|
| Direct variation | y = kx ⇒ y₁/x₁ = y₂/x₂ (ratio constant) |
| Inverse variation | y = k/x ⇒ x₁y₁ = x₂y₂ (product constant) |
| Mean proportional of a and b | √(ab) |
GRE reference
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