SBI PO Linear Equations — Study Material, 10 PYQs & Practice MCQs | ZestExam
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SBI PO Linear Equations
Study Material — 10 PYQs (2018–2018) · Concept Notes · Shortcuts
SBI PO Linear Equations is a frequently tested subtopic — 10 previous year questions from 2018–2018 papers are included below with concept notes, key rules and shortcut tricks.
A merchant mixes two types of rice costing ₹40 per kg and ₹60 per kg in the ratio 3:2. What is the cost per kg of the mixture?
Exam Q 82018Previous Year Pattern
A contractor employs workers for a project. If he hires 10 workers, the project is completed in 12 days. If he hires 15 workers, the project is completed in 8 days. Assuming the work rate per worker is constant, what is the total amount of work (in worker-days)?
Exam Q 92018Previous Year Pattern
A sum of money is divided between Arun and Bhavna in the ratio 5:3. If Arun receives ₹500 more than Bhavna, what is the total sum of money?
Exam Q 102018Previous Year Pattern
A shopkeeper marks up goods by 40% above cost price. He then offers a discount of 25% on the marked price. Later, he realizes he made an error and applies an additional 10% discount on the already discounted price. If the final selling price is ₹945, what is the cost price?
Concept Notes
Linear Equations— Rules & Concept
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Core Concept
Read this first — the foundation of the topic
→Core Concept
Linear equations represent straight lines when plotted on a graph. In SSC CGL, you'll mostly deal with one variable (like x) or two variables (like x and y). The key is finding the value of unknown variables
💡Key Rules
For one variable linear equations like ax + b = 0, the solution is x = -b/a. For two variable systems, you need two equations to find unique solutions. Always maintain balance - whatever you do to one side, do to the other side.
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Formula Block
Memorise — at least one formula appears in every paper
• One variable: ax + b = 0, solution x = -b/a
• Two variables: a1x + b1y = c1 and a2x + b2y = c2
• Elimination method: Multiply equations to make coefficients equal
• Substitution method: Express one variable in terms of another
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Exam Patterns
What examiners ask — read before attempting PYQs
SSC CGL loves testing linear equations through word problems. Age problems, mixture problems, and number problems frequently appear. Questions often involve finding two numbers given their sum and difference, or determining speeds and distances. Expect 2-3 questions per paper.
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Shortcuts
Use these to save 30–60 seconds per question
For sum-difference problems, use this lightning method. If sum = S and difference = D, then larger number = (S+D)/2 and smaller number = (S-D)/2. This skips the entire equation-solving process.
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Worked Example
Solve this step-by-step before moving on
1
Step 1
Let the numbers be x and y where x > y
2
Step 2
Given equations are x + y = 50 and x - y = 12
3
Step 3
Using shortcut - Larger number = (50+12)/2 = 31
4
Step 4
Smaller number = (50-12)/2 = 19
5
Step 5
Verification: 31 + 19 = 50 ✓ and 31 - 19 = 12 ✓
Answer: The numbers are 31 and 19.
Another Trick: For age problems, always define variables for present ages. If the problem mentions 'after n years' or 'before n years', add or subtract n from present ages respectively.
Common Mistake: Students often confuse the setup in word problems. Read carefully whether the problem asks for present age or future age. Also, many forget to verify their answers by substituting back into original equations. Always cross-check your solutions to avoid silly errors that cost marks in competitive exams.
Key Points to Remember
Linear equation has highest power of variable as 1
For ax + b = 0, solution is x = -b/a
Two equations needed to solve two unknown variables