Compound Interest
View Questions of Compound Interest
Quantitative Aptitude - Compound Interest
1. Compound Interest Basics
- Formula: \( A = P \left(1 + \frac{R}{100n} \right)^{nt} \), where P = principal, R = annual rate, n = compounding frequency, t = years, A = amount.
- Interest earned = A − P.
2. Shortcut Methods
- Annual compounding (n = 1): set \( (1 + R/100)^t \).
- Use binomial expansion for 2-3 years when R is small: \( P(1 + tR/100 + \frac{t(t−1)}{2}(R/100)^2) \).
- Convert CI to approximate interest rate per period when compounding monthly/quarterly.
3. Quick Tips
- For annual growth, double time ≈ \( 72/R \) (Rule of 72).
- Use (1 + R/100)^t tables for recurring exam values.
4. Mistakes to Avoid
- Using simple interest formula instead of compound for reinvested interest.
- Not adjusting R and n to the same time unit.
5. Revision Checklist
- Practice annual, semi‑annual, monthly CI problems.
- Be adept at switching between SI and CI.
Summary: Apply exact formula, use expansion for few years, use rule of 72 for estimation in MCQs.
Topics
- Number System
- H.C.F. & L.C.M.
- Decimal Fractions
- Simplification
- Square Roots & Cube Roots
- Average
- Problems on Numbers
- Problems on Ages
- Surds & Indices
- Percentage
- Operations on Numbers
- Profit & Loss
- Ratio & Proportion
- Partnership
- Chain Rule
- Time & Work
- Pipes & Cistern
- Time & Distance
- Problems on Trains
- Boats & Streams
- Alligation or Mixture
- Simple Interest
- Compound Interest
- Logarithms
- Area
- Volume & Surface Areas
- Mensuration
- Races & Games of Skill
- Calendar
- Clocks
- Stocks & Shares
- Permutations & Combinations
- Probability
- True Discount
- Banker’s Discount
- Heights & Distances
- Odd Man Out & Series
- Algebra
- Divisibility Rules & Remainder Theorem
- Factorials & Power Cycles
- Progressions (A.P., G.P., H.P.)
- Work & Wages
- Set Theory / Venn Diagrams
- Geometry (Lines, Angles, Triangles, Polygons)
- Coordinate Geometry
- Data Interpretation
- Trigonometry
- Statistics (Mean, Median, Mode)
- Arithmetic Operations
- Quadratic Equations
Other Subjects
- Prestressed Concrete
- Fluid Mechanics
- Geotechnical Engineering
- Ground Improvement Techniques
- Groundwater Engineering
- Highway Engineering
- Hydraulics and Hydraulic Machines
- Hydrology
- Irrigation Engineering
- Open Channel Flow
- Pavement Design
- Estimation, Costing and Valuation
- Railway Engineering
- Soil Mechanics
- Strength of Materials
- Structural Analysis
- Surveying
- Traffic Engineering
- Transportation Engineering
- Wastewater Treatment
- Water Supply and Sanitation
- Contracts and Specifications
- Reasoning
- Engineering Mathematics
- Air Pollution and Control
- Bridge Engineering
- Building Materials and Construction
- Concrete Technology
- Construction Equipment
- Construction Planning and Management
- Quantitative Aptitude
- Dam Engineering
- Design of RCC Structures
- Design of Steel Structures
- Drainage Engineering
- Earthquake Engineering
- Engineering Geology
- Engineering Graphics
- Engineering Mechanics
- Environmental Engineering
- General Awareness / General Knowledge (GK)