Percentage— Concepts, Formulas & Shortcuts
- x% of y = xy/100, and x% of y = y% of x (useful shortcut).
- Learn the fraction table: 50% = 1/2, 33⅓% = 1/3, 25% = 1/4, 20% = 1/5, 16⅔% = 1/6, 12.5% = 1/8, 10% = 1/10, 6.25% = 1/16.
- Increase by x% then decrease by x% ⇒ net change = −x²/100 % (always a decrease).
- Successive changes of a% and b% ⇒ net = a + b + ab/100 percent (use signs).
- If A is x% more than B, then B is 100x/(100 + x) % less than A.
- Price rises by x% ⇒ consumption must fall by 100x/(100 + x) % to keep expenditure unchanged.
Percentage Practice Questions with Answers
Attempt each question first, then open the explanation. All 28 questions below are free to read and require no signup.
Q1.What is 25% of 320?
Easy- A70
- B75
- C80
- D85
Percentage question 1 of 28+Show Answer & Explanation
Answer: C. 80
Explanation: 25% = 1/4, so 320/4 = 80.
Q2.If 40% of a number is 120, the number is:
Easy- A240
- B280
- C300
- D320
Percentage question 2 of 28+Show Answer & Explanation
Answer: C. 300
Explanation: Number = 120 × 100/40 = 300.
Q3.A number is increased by 20% and then decreased by 20%. The net change is:
Moderate- ANo change
- B4% increase
- C4% decrease
- D2% decrease
Percentage question 3 of 28+Show Answer & Explanation
Answer: C. 4% decrease
Explanation: 1.2 × 0.8 = 0.96, a 4% decrease. General rule: −x²/100 %.
Q4.A student scoring 30% failed by 30 marks, while another scoring 45% got 15 marks more than the pass mark. The maximum marks are:
Difficult- A200
- B250
- C300
- D350
Percentage question 4 of 28+Show Answer & Explanation
Answer: C. 300
Explanation: The 15% gap equals 30 + 15 = 45 marks → 15% of M = 45 → M = 300.
Q5.A salary is increased by 25%. By what per cent must it be reduced to bring it back to the original?
Moderate- A15%
- B20%
- C22.5%
- D25%
Percentage question 5 of 28+Show Answer & Explanation
Answer: B. 20%
Explanation: Reduction = 25/125 × 100 = 20%.
Q6.If the price of sugar rises by 25%, by how much per cent must a family reduce consumption to keep expenditure unchanged?
Moderate- A15%
- B18%
- C20%
- D25%
Percentage question 6 of 28+Show Answer & Explanation
Answer: C. 20%
Explanation: Reduction = 100 × 25/(100 + 25) = 20%.
Q7.Two numbers are respectively 20% and 50% more than a third number. The first as a percentage of the second is:
Moderate- A75%
- B80%
- C85%
- D90%
Percentage question 7 of 28+Show Answer & Explanation
Answer: B. 80%
Explanation: Take the third as 100 → first = 120, second = 150 → 120/150 × 100 = 80%.
Q8.In a school 70% of the students are boys and there are 504 girls. The total number of students is:
Easy- A1,440
- B1,560
- C1,680
- D1,720
Percentage question 8 of 28+Show Answer & Explanation
Answer: C. 1,680
Explanation: Girls = 30% = 504 → total = 504 × 100/30 = 1,680.
Q9.The population of a town grows 10% every year and is 26,620 after 3 years. Its original population was:
Moderate- A18,000
- B20,000
- C22,000
- D24,000
Percentage question 9 of 28+Show Answer & Explanation
Answer: B. 20,000
Explanation: P × 1.1³ = 26620 → P = 26620/1.331 = 20,000.
Q10.If x% of 250 is 50, then x is:
Easy- A15
- B20
- C25
- D30
Percentage question 10 of 28+Show Answer & Explanation
Answer: B. 20
Explanation: x = 50 × 100/250 = 20.
Q11.What is 15% of 400?
Easy- A45
- B50
- C60
- D75
Percentage question 11 of 28+Show Answer & Explanation
Answer: C. 60
Explanation: 15% of 400 = 0.15 × 400 = 60.
Q12.If 25% of a number is 75, the number is:
Easy- A225
- B250
- C300
- D375
Percentage question 12 of 28+Show Answer & Explanation
Answer: C. 300
Explanation: Number = 75 × 100/25 = 300.
Q13.A number is decreased by 25% and then increased by 25%. The net change is:
Moderate- ANo change
- B6.25% decrease
- C6.25% increase
- D12.5% decrease
Percentage question 13 of 28+Show Answer & Explanation
Answer: B. 6.25% decrease
Explanation: 0.75 × 1.25 = 0.9375, a 6.25% decrease. General rule: −x²/100 %.
Q14.In an election between two candidates, the winner got 60% of the votes and won by 1,200 votes. The total number of votes was:
Moderate- A4,000
- B5,000
- C6,000
- D8,000
Percentage question 14 of 28+Show Answer & Explanation
Answer: C. 6,000
Explanation: The margin is 60% − 40% = 20% of the total = 1,200 → total = 6,000 votes.
Q15.The price of an item is increased by 10% and then by another 20%. The total increase is:
Moderate- A30%
- B31%
- C32%
- D33%
Percentage question 15 of 28+Show Answer & Explanation
Answer: C. 32%
Explanation: 1.10 × 1.20 = 1.32, so the net increase is 32%.
Q16.A student scored 480 marks out of 600. His percentage is:
Easy- A75%
- B78%
- C80%
- D85%
Percentage question 16 of 28+Show Answer & Explanation
Answer: C. 80%
Explanation: 480/600 × 100 = 80%.
Q17.If A's income is 25% more than B's, then B's income is less than A's by:
Moderate- A15%
- B20%
- C22%
- D25%
Percentage question 17 of 28+Show Answer & Explanation
Answer: B. 20%
Explanation: Reduction = 100 × 25/(100 + 25) = 20%.
Q18.60% of the students in a class are girls. If there are 24 boys, the total strength is:
Easy- A48
- B56
- C60
- D72
Percentage question 18 of 28+Show Answer & Explanation
Answer: C. 60
Explanation: Boys = 40% = 24 → total = 24 × 100/40 = 60 students.
Q19.The salary of an employee is reduced by 20% and later increased by 25%. His new salary compared with the original is:
Moderate- A5% less
- Bthe same
- C5% more
- D10% less
Percentage question 19 of 28+Show Answer & Explanation
Answer: B. the same
Explanation: 0.80 × 1.25 = 1.00, so the salary returns exactly to the original.
Q20.If the length of a rectangle is increased by 50%, by what per cent must the breadth be reduced to keep the area unchanged?
Difficult- A25%
- B30%
- C33 1/3%
- D50%
Percentage question 20 of 28+Show Answer & Explanation
Answer: C. 33 1/3%
Explanation: Reduction = 100 × 50/(100 + 50) = 33⅓%.
Q21.What is 20% of 750?
Easy- A120
- B140
- C150
- D160
Percentage question 21 of 28+Show Answer & Explanation
Answer: C. 150
Explanation: 0.20 × 750 = 150.
Q22.If 60% of a number is 240, the number is:
Easy- A360
- B380
- C400
- D420
Percentage question 22 of 28+Show Answer & Explanation
Answer: C. 400
Explanation: Number = 240 × 100/60 = 400.
Q23.45 is what percentage of 180?
Easy- A20%
- B25%
- C30%
- D35%
Percentage question 23 of 28+Show Answer & Explanation
Answer: B. 25%
Explanation: 45/180 × 100 = 25%.
Q24.A number increased by 30% becomes 260. The original number is:
Moderate- A180
- B190
- C200
- D210
Percentage question 24 of 28+Show Answer & Explanation
Answer: C. 200
Explanation: 1.30x = 260 → x = 200.
Q25.The price of a shirt falls from ₹800 to ₹680. The percentage decrease is:
Easy- A12%
- B15%
- C18%
- D20%
Percentage question 25 of 28+Show Answer & Explanation
Answer: B. 15%
Explanation: Decrease = ₹120 on ₹800 → 120/800 × 100 = 15%.
Q26.In a class of 80, 25% failed. The number who passed is:
Easy- A55
- B58
- C60
- D65
Percentage question 26 of 28+Show Answer & Explanation
Answer: C. 60
Explanation: Passed = 75% of 80 = 60 students.
Q27.If a number is first increased by 10% and then by 10% again, the total increase is:
Moderate- A20%
- B21%
- C22%
- D25%
Percentage question 27 of 28+Show Answer & Explanation
Answer: B. 21%
Explanation: 1.1 × 1.1 = 1.21, so the increase is 21%.
Q28.A candidate scoring 40% fails by 20 marks, while the pass mark is 45% of the maximum. The maximum marks are:
Difficult- A300
- B350
- C400
- D450
Percentage question 28 of 28+Show Answer & Explanation
Answer: C. 400
Explanation: The 5% gap equals 20 marks → 5% of M = 20 → M = 400.
Percentage — Frequently Asked Questions
If my salary is cut 20% then raised 20%, do I get back to the original?+
No. The net effect is a 4% decrease, because the 20% rise is applied to a smaller base. The general result is −x²/100 %.
How do I convert a percentage to a fraction quickly?+
Memorise the standard table up to 1/16. In exams, 37.5% instantly becoming 3/8 saves more time than any other single shortcut.
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