Study Material — 5 PYQs (2018–2020) · Concept Notes · Shortcuts
NDA Percentage Word Problems is a frequently tested subtopic — 5 previous year questions from 2018–2020 papers are included below with concept notes, key rules and shortcut tricks.
NDA Percentage Word Problems — Past Exam Questions
5 questions from actual NDA papers · all shown free · click option to reveal solution
Exam Q 12018Previous Year Pattern
A student scored 450 marks out of 600 in an examination. What percentage of marks did the student score?
Exam Q 22020Previous Year Pattern
A shopkeeper marks up the price of an item by 40% above its cost price. If he then offers a discount of 20% on the marked price, what is his profit percentage?
Exam Q 32019Previous Year Pattern
A shopkeeper marks up the price of an item by 40% above its cost price. During a sale, he offers a discount of 25% on the marked price. If the cost price of the item is ₹800, what is his profit percentage?
Exam Q 42018Previous Year Pattern
In an election between two candidates, the winning candidate got 60% of the total votes cast. If the winning candidate won by 480 votes, what was the total number of votes cast?
Exam Q 52020Previous Year Pattern
A shopkeeper marks up the cost price of an item by 40%. During a sale, he offers a discount of 25% on the marked price. If the cost price of the item is ₹800, what is his profit percentage?
Concept Notes
Percentage Word Problems— Rules & Concept
Core ConceptRead this first — the foundation of the topic
Core Concept
Percentage word problems involve finding parts of a whole, comparing quantities, or calculating increases and decreases in real scenarios like salary hikes, discounts, population growth, and election results
Key Rules
Always identify the base value first. The base is usually mentioned after 'of' or 'than'. When percentage increases, new value = original + increase. When percentage decreases, new value = original - decrease.
In comparison problems, identify which quantity is 100%.
Formula BlockMemorise — at least one formula appears in every paper
- Percentage = (Part/Whole) × 100
- Increase% = (Increase/Original) × 100
- Decrease% = (Decrease/Original) × 100
- New value after x% increase = Original × (100+x)/100
- New value after x% decrease = Original × (100-x)/100
- If A is x% more than B, then B is [x/(100+x)] × 100% less than A
Exam PatternsWhat examiners ask — read before attempting PYQs
SSC CGL typically asks about salary changes, price variations, population problems, election results, and mixture problems. Questions often involve successive percentage changes or finding original values when final values are given.
Powerful Shortcut - The 'Of-Is' Method: In any percentage problem, identify the 'OF' value (base/whole) and 'IS' value (part). Then use: Percentage = (IS/OF) × 100. This works for all percentage word problems.
Worked ExampleSolve this step-by-step before moving on
1
Step 1
Let original salary = x
2
Step 2
After 20% increase = x × 120/100 = 1.2x
3
Step 3
After 15% decrease = 1.2x × 85/100 = 1.02x
4
Step 4
Given final salary = 10,200
5
Step 5
So, 1.02x = 10,200
6
Step 6
x = 10,200/1.02 = 10,000
Therefore, original salary = Rs. 10,000
Another Shortcut: For successive percentage changes, if there are a% increase followed by b% decrease, net effect = [a - b - (ab/100)]%. If positive, it's increase; if negative, it's decrease.
Using this shortcut: Net effect = 20 - 15 - (20×15/100) = 5 - 3 = 2% increase
So final salary = original × 1.02 = 10,200
Original = 10,200/1.02 = 10,000
Exam TrapsCommon mistakes students make — avoid these
Students often confuse the base value. Remember, percentages are always calculated on the original or given base value, not on intermediate results unless specifically mentioned.
Key Points to Remember
Always identify the base value first - it usually comes after 'of' or 'than'
Use 'Of-Is' method: Percentage = (IS value/OF value) × 100
For successive changes: Net effect = a - b - (ab/100) when a% increase then b% decrease
New value after x% increase = Original × (100+x)/100
New value after x% decrease = Original × (100-x)/100
If A is x% more than B, then B is [x/(100+x)] × 100% less than A
In comparison problems, identify which quantity represents 100%
Percentage increase/decrease is always calculated on the original value
Exam-Specific Tips
If price increases by 25%, consumption must decrease by 20% to keep expenditure same
When A is 20% more than B, then B is 16.67% less than A
Successive increases of 10% and 20% give net increase of 32%
If population grows by 10% annually, it becomes 1.21 times in 2 years
50% of 40% = 20% (multiply percentages by dividing by 100)
In elections with two candidates, if winner gets 60%, margin of victory is 20%
If salary increases by 15% and tax by 10%, effective increase is 5% on net income
Practice MCQs
Percentage Word Problems — Practice Questions
50graded MCQs · easy to hard · full solution & trap analysis · showing 20 of 50
In an examination, 65% of students passed in English and 75% passed in Mathematics. If 15% of students failed in both subjects, what percentage of students passed in both subjects?
Practice 2easy
A shopkeeper marks his goods at 40% above the cost price. If he gives a discount of 10% on the marked price, what is his profit percentage?
Practice 3easy
A student scores 45% in an exam and fails by 15 marks. If he had scored 55%, he would have passed by 5 marks. What is the passing mark for the exam?
Practice 4easy
In an examination, 35% of students failed in Mathematics and 28% failed in English. If 10% failed in both subjects, what percentage of students passed both subjects?
Practice 5easy
A student scored 65% marks in English and 72% marks in Mathematics. If English has a weightage of 40% and Mathematics has a weightage of 60%, what is the student's overall percentage?
Practice 6easy
A shopkeeper marks up the price of an item by 40%. If he then gives a discount of 10% on the marked price, what is his profit percentage?
Practice 7easy
In an election, candidate A received 55% of the votes and candidate B received the remaining votes. If the total number of votes cast was 8000, how many more votes did A receive than B?
Practice 8easy
A shopkeeper marks his goods 40% above the cost price. If he gives a discount of 10% on the marked price, what is his profit percentage?
Practice 9easy
A shopkeeper marks an item at ₹500. He offers a discount of 20% on the marked price. What is the selling price?
Practice 10easy
A student scored 72% in an exam and obtained 360 marks. What were the total marks of the exam?
Practice 11easy
The population of a town decreased by 12% in one year. If the population is now 22,000, what was it a year ago?
Practice 12easy
The price of a commodity increases by 20%. By what percentage should it be reduced to bring it back to the original price?
Practice 13easy
The price of petrol increased by 20%. A consumer wants to spend the same amount of money as before. By what percentage should he reduce his consumption?
Practice 14easy
A student scored 45% marks in an examination and failed by 36 marks. Another student scored 65% marks and passed by 24 marks. What is the passing percentage?
Practice 15easy
A number is increased by 25%, and then the result is decreased by 20%. What is the net change in the original number?
Practice 16easy
A shopkeeper bought an item for ₹600 and sold it at a profit of 25%. What is the selling price?
Practice 17easy
The price of a commodity increases by 20% in the first year and decreases by 25% in the second year. What is the net percentage change in the price over two years?
Practice 18easy
In an examination, 65% of students passed. If 520 students passed, how many students appeared in total?
Practice 19easy
A mobile phone's price increased by 15% from last year. If the price last year was ₹8000, what is the current price?
Practice 20easy
A salary is increased by 15% in the first year and by 10% in the second year. What is the total percentage increase over the two years?
30 more practice questions in the Study Panel
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