All Exams: Quantitative Aptitude — Percentage (2026)

Percentage: Core Concepts

Basic Formula: Percentage = (Part/Whole) × 100

% Increase/Decrease: Change/Original × 100

Percentage to Fraction: 10%=1/10, 20%=1/5, 25%=1/4, 33.33%=1/3, 50%=1/2.

Successive Changes: Two changes of a% and b% → Net = a+b+ab/100%

⚡ Key Insight: If A is x% more than B, then B is x/(100+x)×100% less than A. Example: A is 25% more than B → B is 20% less than A.

Exam-Relevant Applications

  • Discount problems (% on marked price)
  • Population growth/decline
  • Election vote percentages
  • Mixture concentration problems

Practice MCQs — Percentage

Q1. 20% of 150?

  • A) 25
  • B) 30
  • C) 35
  • D) 40
Answer: B) 30 — 150×20/100=30.

Q2. A number increased by 30% becomes 169. Find original?

  • A) 100
  • B) 120
  • C) 130
  • D) 150
Answer: C) 130 — 130% of x=169 → x=130.

Q3. A shop gives 20% discount on marked price ₹500. SP?

  • A) ₹380
  • B) ₹400
  • C) ₹420
  • D) ₹450
Answer: B) ₹400 — 500×80/100=₹400.

Q4. Population increases 10% annually. After 2 years from 10000?

  • A) 11000
  • B) 11100
  • C) 12100
  • D) 12200
Answer: C) 12100 — 10000×1.1²=12100.

Q5. If 60% of X = 30% of 400. Find X?

  • A) 150
  • B) 200
  • C) 250
  • D) 300
Answer: B) 200 — 0.6X=120 → X=200.

Q6. What % is 75 of 500?

  • A) 10%
  • B) 12%
  • C) 15%
  • D) 20%
Answer: C) 15% — 75/500×100=15%.

Q7. A's salary is 25% more than B's. B's is what % less than A's?

  • A) 16%
  • B) 20%
  • C) 25%
  • D) 30%
Answer: B) 20% — If B=100, A=125. B less than A by 25/125×100=20%.

Q8. Fail % in exam = 30%. Pass = 420. Total students?

  • A) 550
  • B) 580
  • C) 600
  • D) 630
Answer: C) 600 — 70% of total=420 → total=600.

Q9. Price falls 20% then rises 25%. Net change?

  • A) 0%
  • B) 2%
  • C) 3%
  • D) 5%
Answer: A) 0% — 100×0.8×1.25=100. Net=0%.

Q10. If A spends 70% income and saves ₹3000, income?

  • A) ₹8000
  • B) ₹9000
  • C) ₹10000
  • D) ₹12000
Answer: C) ₹10000 — 30% saved=₹3000 → income=₹10000.