मात्रात्मक अभिरुचि (Quantitative Aptitude)

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मात्रात्मक अभिरुचि — Topic Weight Distribution 20% Percentage

15% Ratio

15% SI/CI

12% Time-Work

12% Profit/Loss

10% Speed-Time

8% Geometry

Approximate distribution based on SSO exam pattern

1. Percentage (प्रतिशत)

मुख्य Formulas

Concept Formula
% of a number x% of N = (x/100)×N
% increase [(New−Old)/Old]×100
% decrease [(Old−New)/Old]×100
A is what % of B (A/B)×100
Successive % a+b+(ab/100)

Fraction-Percent Conversion (याद गर्नुस्)

Fraction % Fraction %
1/2 50% 1/8 12.5%
1/3 33.33% 1/9 11.11%
1/4 25% 1/11 9.09%
1/5 20% 2/3 66.67%
1/6 16.67% 3/4 75%

2. Ratio र Proportion (अनुपात)

Key Concepts

Type Formula Example
Basic ratio a:b = ka:kb 2:3 = 4:6
Compound ratio (a:b)×(c:d) = ac:bd 2:3 × 3:4 = 6:12 = 1:2
Mean proportion a:x = x:b → x=√(ab) 4:x=x:9 → x=6
Mixture rule (Alligation) (Q1/Q2)=(C2−Mean)/(Mean−C1) सस्तो-महँगो mix

3. Simple र Compound Interest

Simple Interest (SI)

SI = PRT/100
Amount = P + SI
P = Principal, R = Rate%, T = Time(yr)

Compound Interest (CI)

A = P(1+R/100)ⁿ
CI = A − P
Half-yearly: R/2, n×2
Quarterly: R/4, n×4

CI vs SI (2 years): CI − SI = P(R/100)² → Difference formula

4. Profit र Loss (नाफा-नोक्सान)

Formulas

Concept Formula
Profit % [(SP−CP)/CP]×100
Loss % [(CP−SP)/CP]×100
SP (given P%) CP×(100+P%)/100
CP (given SP, P%) SP×100/(100+P%)
Dishonest dealer Gain % = [Error/(True wt − Error)]×100

5. Time, Work र Pipes

Key Formulas

Case Formula
A ले n दिनमा काम गर्छ → 1 दिनको काम 1/n
A र B मिलेर 1/A + 1/B = 1/Total days
A ले n दिनमा भर्छ, B ले m दिनमा खाली गर्छ Time = nm/(m−n)
Efficiency ratio a:b → Time ratio b:a (inverse)

6. Speed, Distance, Time

Concept Formula
Basic Distance = Speed × Time
Average speed (same distance) 2xy/(x+y)
Relative speed (same direction) |S1−S2|
Relative speed (opposite) S1+S2
Train crossing pole Time = Length/Speed
Train crossing platform Time = (Train+Platform length)/Speed
km/hr → m/s ×5/18
m/s → km/hr ×18/5

7. Mensuration (क्षेत्रमिति)

2D Shapes

Shape Area Perimeter
Triangle ½ × b × h a+b+c
Rectangle l × b 2(l+b)
Square 4a
Circle πr² 2πr
Trapezium ½(a+b)×h

3D Shapes

Shape Volume CSA
Cube 4a²
Cuboid lbh 2h(l+b)
Cylinder πr²h 2πrh
Cone ⅓πr²h πrl
Sphere 4/3πr³ 4πr²
Quick Recall — Quantitative:
• % succession: a+b+ab/100
• SI = PRT/100 | CI: A=P(1+r/n)^nt
• CI−SI (2yr) = P(R/100)²
• Profit/Loss % always on CP
• Avg speed (same dist) = 2xy/(x+y)
• km/hr × 5/18 = m/s
• Circle: Area=πr², Perimeter=2πr
• Cylinder Volume = πr²h
Practice MCQs:
Q1. एउटा वस्तु Rs.800 मा किनेर Rs.1000 मा बेचियो। नाफा प्रतिशत?
(A) 20%   (B) 25%   (C) 30%   (D) 15%
→ (B) 25% → (200/800)×100=25%

Q2. 60 km/hr को m/s मा रूपान्तरण?
(A) 16.67 m/s   (B) 20 m/s   (C) 18 m/s   (D) 15 m/s
→ (A) 16.67 → 60×5/18 = 16.67

Q3. A ले 10 दिनमा र B ले 15 दिनमा काम गर्छ। दुवैले मिलेर कति दिनमा?
(A) 5   (B) 6   (C) 7   (D) 8
→ (B) 6 → LCM(10,15)=30; A=3/day, B=2/day; Total=5/day; Days=30/5=6