GED Percent Word Problems: The Complete "How to Solve" Guide

GED Percent Word Problems: The Complete "How to Solve" Guide

(1,200+ words – Every line is actionable under timed conditions)

Introduction

"Percent word problems show up 4-6 times on the GED Math test—master them, and you’ll gain 10-15 raw points, pushing you into the next scoring tier (150+ to 165+)."

WHAT THIS QUESTION TYPE IS ACTUALLY TESTING

The GED isn’t testing your ability to calculate percentages—it’s testing: 1. Reading precision – Can you extract the exact numbers and relationships from dense wording? 2. Decision discipline – Can you avoid rushing into calculations before identifying what’s being asked? 3. Trap resistance – Can you spot the 4 classic wrong-answer patterns that derail 80% of test-takers?

ANATOMY OF THE QUESTION

Structure Breakdown

Representative Example Question

"A laptop is on sale for $480 after a 20% discount. What was the original price of the laptop?" - Stem: Laptop sale scenario. - Conditions: Final price = $480, discount = 20%. - Question: Find the original price. - Answer Choices: A) $384 B) $576 C) $600 D) $620

THE DECISION FRAMEWORK (Step-by-Step)

Run this process for every percent word problem. No exceptions.

Step 1: Identify the "Known" and "Unknown"

• Known: The numbers given (e.g., $480, 20%).
• Unknown: What the question is asking for (e.g., original price).
• Action: Circle the unknown in the question.

Step 2: Translate Words into an Equation

• Key Phrases → Math:
• "X is 20% of Y" → X = 0.20 × Y
• "X is 20% more than Y" → X = Y + 0.20Y = 1.20Y
• "X is 20% less than Y" → X = Y – 0.20Y = 0.80Y
• Action: Write the equation before calculating.

Step 3: Solve for the Unknown

• If the unknown is the original amount (e.g., pre-discount price):
• Final amount = Original × (1 ± percent change).
• Rearrange to solve for original.
• If the unknown is the percent change:
• Percent change = (Change / Original) × 100.
• Action: Plug in numbers and solve.

Step 4: Check Units and Reasonableness

• Units: Does the answer make sense? (e.g., original price > sale price).
• Reasonableness: Is the answer in the ballpark? (e.g., 20% off $600 = $480, not $384).
• Action: Eliminate answers that violate logic.

Step 5: Match to Answer Choices

• Action: Compare your solution to the options. If no match, recheck Steps 1-4.

Worked Examples

Example 1: Straightforward (Discount Problem)

Question: "A jacket is on sale for $60 after a 25% discount. What was the original price?"

Step 1: Known and Unknown

• Known: Sale price = $60, discount = 25%.
• Unknown: Original price.

Step 2: Translate to Equation

• Sale price = Original price × (1 – discount).
• $60 = Original × (1 – 0.25) → $60 = Original × 0.75.

Step 3: Solve

• Original = $60 / 0.75 = $80.

Step 4: Check Reasonableness

• 25% off $80 = $20 discount → $60 sale price. ✔️

Step 5: Match to Choices

• Correct answer: $80 (not listed here, but process is key).

Example 2: Common Trap (Markup + Discount)

Question: "A store marks up a shirt by 50% and then offers a 20% discount. If the final price is $36, what was the original cost?"

Step 1: Known and Unknown

• Known: Markup = 50%, discount = 20%, final price = $36.
• Unknown: Original cost.

Step 2: Translate to Equation

• After markup: Price = Original × 1.50.
• After discount: Final price = (Original × 1.50) × 0.80.
• $36 = Original × 1.20.

Step 3: Solve

• Original = $36 / 1.20 = $30.

Step 4: Check Reasonableness

• $30 + 50% = $45.
• $45 – 20% = $36. ✔️

Step 5: Match to Choices

• Trap: Students might calculate 50% – 20% = 30% and use $36 / 0.70 = $51.43 (wrong).
• Correct answer: $30.

Example 3: Hard Variant (Successive Percent Changes)

Question: "A population grows by 10% in Year 1 and then decreases by 10% in Year 2. If the final population is 99,000, what was the original population?"

Step 1: Known and Unknown

• Known: Year 1 growth = +10%, Year 2 decrease = –10%, final = 99,000.
• Unknown: Original population.

Step 2: Translate to Equation

• After Year 1: Population = Original × 1.10.
• After Year 2: Population = (Original × 1.10) × 0.90 = Original × 0.99.
• 99,000 = Original × 0.99.

Step 3: Solve

• Original = 99,000 / 0.99 = 100,000.

Step 4: Check Reasonableness

• 100,000 + 10% = 110,000.
• 110,000 – 10% = 99,000. ✔️

Step 5: Match to Choices

• Trap: Students might average the percents (0%) and guess 99,000 (wrong).
• Correct answer: 100,000.

WRONG ANSWER PATTERNS

Common Mistakes

TIME STRATEGY

• Target Time: 1 minute per question.
• When to Skip: If you can’t identify the known/unknown in 20 seconds, flag and return.
• Minimum Work: Write the equation and solve—no shortcuts until you’ve mastered the framework.

BACKSOLVING AND SHORTCUTS

1. Plug in Answer Choices:
2. Start with the middle option (B or C) to eliminate two at once.

3. Example: For the laptop question, test $600 (Option C):

   • 20% of $600 = $120 discount → $600 – $120 = $480. ✔️

4. Use 100 as a Base:

5. For problems with unknown original amounts, assume 100 and scale.

6. Example: If 20% off gives $480, then 100% – 20% = 80% → $480 / 0.80 = $600.

7. Eliminate Impossible Answers:

8. Original price must be > sale price (for discounts).
9. Final amount after growth must be > original.

1-Minute Recap

"Here’s your 60-second battle plan for percent word problems on the GED: 1. Circle the unknown—what’s the question really asking? 2. Write the equation—translate words into math before calculating. 3. Solve step-by-step—no shortcuts until you’ve nailed the framework. 4. Check for traps—did you reverse the percent? Add instead of multiply? 5. Match to choices—if your answer isn’t there, recheck your base.

Remember: The GED is testing your discipline, not your speed. Slow down, follow the steps, and those 4-6 questions will be free points. Now go practice—timed!

Final Note

This framework works for every percent word problem on the GED. Print this guide, drill 10 problems using the steps, and watch your score climb. No exceptions.