Data Sufficiency: Ratio and Proportion Sufficiency

Concept Explanation

Ratio DS problems test whether statements fix quantities in a given ratio or proportional relationship.

Standard Answer Choices

• A — Statement I alone is sufficient; Statement II alone is not.
• B — Statement II alone is sufficient; Statement I alone is not.
• C — Both together are sufficient, neither alone.
• D — Either statement alone is sufficient.
• E — Neither alone nor together is sufficient.

Ratio DS Focus

Convert ratios to parts, use multiplier k, and check whether statements give k or enough totals.

DS Decision Flow

1. State exactly what must be determined (number, ratio, yes/no, or comparison).
2. Test Statement I alone—sufficient or insufficient?
3. Test Statement II alone—sufficient or insufficient?
4. If neither alone works, combine both statements.
5. Choose A–E based on sufficiency; never pick a value when data do not fix it uniquely.

Common Traps in Ratio Problems

• Adding ratios without a common total.
• Confusing ratio with actual count.
• Assuming proportionality across unrelated quantities.