SSC GD Constable Fractions & Decimals — Study Material, 4 PYQs & Practice MCQs | ZestExam
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SSC GD Constable Fractions & Decimals
Study Material — 4 PYQs (2019–2019) · Concept Notes · Shortcuts
SSC GD Constable Fractions & Decimals is a frequently tested subtopic — 4 previous year questions from 2019–2019 papers are included below with concept notes, key rules and shortcut tricks.
The ratio of two numbers is 7:5. If their difference is 24, what is the smaller number?
Exam Q 42019Previous Year Pattern
If 0.6 of a quantity equals 120, what is 0.35 of that quantity?
Concept Notes
Fractions & Decimals— Rules & Concept
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Core Concept
Read this first — the foundation of the topic
Core Concept: Fractions represent parts of a whole. A fraction has two parts - numerator (top number) and denominator (bottom number). Decimals are another way to write fractions using place values after a decimal point.
Both are extensively tested in SSC CGL.
Key Rules and Properties: Every fraction can be converted to decimal form by dividing numerator by denominator. Terminating decimals have denominators with only factors of 2 and 5. Non-terminating decimals have denominators with factors other than 2 and 5.
When adding fractions, find common denominator first. When multiplying fractions, multiply numerators together and denominators together.
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Formula Block
Memorise — at least one formula appears in every paper
Fraction to Decimal: Numerator ÷ Denominator
Decimal to Fraction: Remove decimal, divide by appropriate power of 10
Addition: a/b + c/d = (ad + bc)/(bd)
Subtraction: a/b - c/d = (ad - bc)/(bd)
Multiplication: a/b × c/d = (ac)/(bd)
Division: a/b ÷ c/d = (ad)/(bc)
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Exam Patterns
What examiners ask — read before attempting PYQs
SSC CGL frequently asks fraction comparisons, decimal conversions, arithmetic operations with mixed numbers, and word problems involving parts of quantities. Questions often involve finding equivalent fractions, simplifying complex fractions, and converting recurring decimals to fractions.
Shortcut - Cross Multiplication for Comparison: To compare fractions a/b and c/d, multiply a×d and b×c. If a×d > b×c, then a/b > c/d. This saves time over finding common denominators.
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Worked Example
Solve this step-by-step before moving on
1
Step 1
Cross multiply - 7×6 = 42 and 9×5 = 45
2
Step 2
Compare results - 42 < 45
3
Step 3
Therefore 7/9 < 5/6
Converting Recurring Decimal 0.363636... to Fraction:
1
Step 1
Let x = 0.363636...
2
Step 2
Multiply by 100 (since 2 digits repeat): 100x = 36.363636...
3
Step 3
Subtract original: 100x - x = 36
4
Step 4
Solve: 99x = 36, so x = 36/99 = 4/11
5
Step 5
Verify: 4÷11 = 0.363636... ✓
Another Shortcut - Decimal Place Memory: For quick conversions, remember that 1/8 = 0.125, 1/3 = 0.333..., 1/6 = 0.1666..., 1/7 = 0.142857... (repeating). These frequently appear in options.
Common Mistake: Students often forget to simplify fractions to lowest terms or make errors with recurring decimals. Always reduce fractions by finding the highest common factor of numerator and denominator. Also, when dealing with mixed numbers, convert to improper fractions first before performing operations.
Key Points to Remember
Fraction = Numerator/Denominator represents parts of a whole number
Terminating decimals have denominators with only factors 2 and 5
Cross multiplication shortcut: a/b vs c/d compare a×d with b×c
To add fractions: a/b + c/d = (ad + bc)/(bd)
Recurring decimal with n repeating digits: multiply by 10^n then subtract
Mixed number operations: convert to improper fractions first
Always simplify final answers using HCF of numerator and denominator
1/7 = 0.142857... (6-digit repetition) appears frequently in SSC
A decimal number 0.8̄3̄ (where both 8 and 3 repeat) is converted to a fraction. If this fraction is multiplied by 5/6 and then 2/5 is subtracted from the result, what is the final answer?
Practice 2hard
A shopkeeper mixes two types of flour. Type A costs ₹45 per kg and Type B costs ₹60 per kg. He mixes them in the ratio 5:3 and sells the mixture at ₹58 per kg. What is his profit percentage on the cost price of the mixture?
60-Second Revision — Fractions & Decimals
Remember: Cross multiply to compare fractions quickly without finding LCM
Formula: Recurring decimal conversion - multiply by 10^n, subtract, solve
Trap: Always check if fraction can be simplified using HCF