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TNPSC percentage practice questions with worked answers

By the PrepMatic team · Updated 9 Oct 2026 · 3 min read

Percentage is the first topic to master in TNPSC aptitude, because it underlies profit and loss, interest, data tables and many everyday word problems. Part C of the Group 4 paper has 25 questions on aptitude and mental ability (15 aptitude and 10 reasoning), worth 37.5 of the 300 marks, and percentage is one of the ten aptitude topics the notification lists. The five questions below are SSLC-level and each answer is worked out in full. See also the TNPSC aptitude and mental ability guide.

What this topic covers

• Basic conversions: percentages, fractions and decimals.
• Percentage of a quantity: finding x per cent of a number and the reverse.
• Change: increase, decrease and successive changes.
• Applications: marks, population, price changes and mixtures at a simple level.

Sample questions

Question 1

What is 35% of 240?

• A. 72
• B. 96
• C. 105
• D. 84

Question 2

A town has a population of 20,000. It increases by 10% in the first year and by 10% in the second year. The population after two years is:

• A. 24,000
• B. 22,000
• C. 24,200
• D. 26,000

Question 3

The price of a book is reduced from ₹250 to ₹200. The percentage decrease is:

• A. 20%
• B. 15%
• C. 25%
• D. 50%

Question 4

A number increased by 20% becomes 180. The number is:

• A. 144
• B. 150
• C. 160
• D. 216

Question 5

A student who scored 360 marks failed by 40 marks. If the pass mark is 40%, the maximum marks in the exam are:

• A. 800
• B. 900
• C. 1,000
• D. 1,200

Answers and explanations

1. D. 35% of 240 = 35 ÷ 100 × 240 = 84. A quick route: 10% of 240 is 24, so 30% is 72 and 5% is 12, which gives 72 + 12 = 84.
2. C. After the first year: 20,000 × 1.10 = 22,000. After the second year: 22,000 × 1.10 = 24,200. The tempting answer 24,000 adds the two 10% increases and ignores that the second one applies to the larger number. The formula gives 10 + 10 + (10 × 10) ÷ 100 = 21%, and 21% of 20,000 is 4,200.
3. A. The decrease is 250 − 200 = ₹50. As a percentage of the original: 50 ÷ 250 × 100 = 20%.
4. B. Original = 180 × 100 ÷ 120 = 150. Check: 20% of 150 is 30, and 150 + 30 = 180. Taking 20% off 180 instead gives 144, which is a common wrong answer.
5. C. The pass mark is 360 + 40 = 400. If 40% of the maximum is 400, the maximum is 400 × 100 ÷ 40 = 1,000.

How to prepare percentage

Learn the fraction equivalents first. Knowing that 12.5% is 1/8, 16.67% is 1/6, 20% is 1/5, 25% is 1/4, 33.33% is 1/3 and 37.5% is 3/8 turns many questions into simple division. Write the list on a card, cover the right-hand side, and test yourself for five minutes a day for a week.

Next, practise the change questions in a fixed order: identify the original value, identify the new value, then decide which one you divide by. Almost every error in this chapter comes from dividing by the new value when the question wants the change on the original value.

Finally, learn to check an answer by substitution. In question 4, for example, you can test an option in seconds. This is fast in an OMR exam because TNPSC gives you four options, and checking an option costs less time than solving from scratch.

Move on to TNPSC ratio and proportion practice and TNPSC simplification practice, which use the same fraction-and-decimal fluency.

Take the full topic test on PrepMatic

PrepMatic topic tests give you about 15 questions in 30 minutes, which is a realistic way to practise speed, not just accuracy. Your analytics show speed per question and accuracy over time. A 25-question aptitude and reasoning section in a 180-minute paper deserves a time budget, and the topic test helps you set one.

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