Ratios and Proportions · Sub-skill drill
Setting Up Proportions
A proportion equates two ratios: a/b = c/d. The setup matters enormously: the same units must appear in the same position across the equation. If the left ratio is miles per hour, the right ratio must also be miles per hour, not hours per mile. Students who set up proportions inconsistently get the reciprocal of the correct answer, which the College Board reliably lists as a wrong-answer choice. Cross-multiplying after a clean setup gives ad = bc, which solves in one step.
How this sub-skill is tested on the SAT
A proportion equates two ratios: a/b = c/d. The setup matters enormously: the same units must appear in the same position across the equation. If the left ratio is miles per hour, the right ratio must also be miles per hour, not hours per mile. Students who set up proportions inconsistently get the reciprocal of the correct answer, which the College Board reliably lists as a wrong-answer choice. Cross-multiplying after a clean setup gives ad = bc, which solves in one step.
This sub-skill sits inside the broader Ratios and Proportions topic, which is part of the College Board's Problem Solving & Data Analysis content domain. Problem Solving and Data Analysis is where the SAT pretends to be the real world. Every question in this domain is wrapped in context: a recipe, a survey, a clinical trial, a lab measurement, a marketing report. The math itself is rarely harder than middle-school arithmetic — ratios, proportions, percentages, unit conversions, means, medians, scatter plots, two-way tables, and basic probability. What trips students up is the reading. The College Board has spent two decades calibrating these prompts to reward students who slow down on the setup and punish students who rush to compute. ScoreRe
Practice questions in this drill set
Below are 7 practice questions targeting this exact sub-skill, ordered from easier to harder. Each question is tagged with its target score band so you can focus on questions that match the band you are working out of. Worked solutions are open by default — read each one even if you got the question right, because the way the solution is structured often reveals a faster path than the one you used.
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In a class, the ratio of seniors to juniors is 7:6. If there are 143 students total, how many are seniors?
- A 77
- B 66
- C 13
- D 65
Worked solution
Answer: A — 77
The ratio 7:6 means seniors make up 7/13 of the total. Multiply: (7/13) × 143 = 77 seniors. As a check, juniors are 66 and 77 + 66 = 143.
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In a class, the ratio of seniors to juniors is 8:9. If there are 119 students total, how many are seniors?
- A 63
- B 62
- C 17
- D 56
Worked solution
Answer: D — 56
The ratio 8:9 means seniors make up 8/17 of the total. Multiply: (8/17) × 119 = 56 seniors. As a check, juniors are 63 and 56 + 63 = 119.
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In a class, the ratio of seniors to juniors is 9:2. If there are 132 students total, how many are seniors?
- A 24
- B 23
- C 11
- D 108
Worked solution
Answer: D — 108
The ratio 9:2 means seniors make up 9/11 of the total. Multiply: (9/11) × 132 = 108 seniors. As a check, juniors are 24 and 108 + 24 = 132.
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In a class, the ratio of seniors to juniors is 6:9. If there are 135 students total, how many are seniors?
- A 81
- B 15
- C 54
- D 80
Worked solution
Answer: C — 54
The ratio 6:9 means seniors make up 6/15 of the total. Multiply: (6/15) × 135 = 54 seniors. As a check, juniors are 81 and 54 + 81 = 135.
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In a class, the ratio of seniors to juniors is 6:6. If there are 144 students total, how many are seniors?
- A 72
- B 12
- C 73
- D 71
Worked solution
Answer: A — 72
The ratio 6:6 means seniors make up 6/12 of the total. Multiply: (6/12) × 144 = 72 seniors. As a check, juniors are 72 and 72 + 72 = 144.
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In a class, the ratio of seniors to juniors is 7:3. If there are 70 students total, how many are seniors?
- A 21
- B 20
- C 10
- D 49
Worked solution
Answer: D — 49
The ratio 7:3 means seniors make up 7/10 of the total. Multiply: (7/10) × 70 = 49 seniors. As a check, juniors are 21 and 49 + 21 = 70.
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In a class, the ratio of seniors to juniors is 8:4. If there are 48 students total, how many are seniors?
- A 32
- B 15
- C 12
- D 16
Worked solution
Answer: A — 32
The ratio 8:4 means seniors make up 8/12 of the total. Multiply: (8/12) × 48 = 32 seniors. As a check, juniors are 16 and 32 + 16 = 48.
Why this band assignment matters
Every question in this drill is tagged with a target score band — 400–500, 500–600, 600–700, or 700–800 — based on its difficulty and the patterns the College Board uses for questions at each level. If you are aiming to break out of a 580 plateau, the 600–700 questions in this drill are your highest-leverage practice. If you are chasing 750+, the 700–800 questions here are the ones that separate the top 10% of test takers from everyone else.
Use the band tags to filter your work. If you can confidently solve every 400–500 and 500–600 question without notes, move to the 600–700 set. If those land cleanly, the 700–800 set is your final boss. The worked solutions in this drill are written so that even the hardest questions become learnable patterns once you have seen the structure of the solve a few times.