Summary of "Aptitude Made Easy – Problems on Percentages full series, Learn maths #StayHome"

Main Ideas and Concepts

Understanding Percentages
Percentages represent a part of a whole expressed in terms of 100. The numerator in a percentage calculation is referred to as the "rate percent."
Basic Calculations
To find a percentage of a number, divide the numerator by the denominator (100) and multiply by the number in question. Example: To find what percent 3 is of 60, use the formula: (3/60) * 100 = 5%.
Conversion Between Percentages and Fractions
To convert a percentage to a fraction, divide by 100. To convert a fraction to a percentage, multiply by 100. Example: 20% = 20/100 = 1/5; 1/5 = 20%.
Memorization of Key Fractions
Memorize the values of fractions from 1/1 to 1/10 and their corresponding percentages for quick calculations. Example: 1/3 = 33.33%, 1/4 = 25%, etc.
Common Percentage Problems
- Finding Percentages: X is what percent of Y is calculated as (X/Y) * 100.
- Increasing/Decreasing Values by a Percentage:
  - For an increase of X%, the new value = (1 + X/100) * original value.
  - For a decrease of X%, the new value = (1 - X/100) * original value.
Salary Problems
Understanding how to calculate the percentage difference between salaries. Example: If Kanish's salary is 20% more than Ashok's, calculate how much less Ashok's salary is compared to Kanish's.
Expenditure Problems
The relationship between rate, consumption, and expenditure is crucial. If the rate increases, the consumption must decrease to keep expenditure constant. Example: If the rate increases by 50%, the consumption must decrease by 33.33% to maintain the same expenditure.
Formula for Combined Percentage Changes
When two values are increased by percentages A and B, the overall change can be calculated using the formula: A + B + (AB/100).

Methodology and Instructions

Convert Percentages to Fractions: Divide the percentage by 100.
Convert Fractions to Percentages: Multiply the fraction by 100.
Calculate Percentage of a Number: Use the formula (X/Y) * 100.
Find New Values After Increase/Decrease:
- Increase: New Value = Original Value * (1 + X/100)
- Decrease: New Value = Original Value * (1 - X/100)
Salary Comparisons: Set a base value (e.g., 100) for easier calculations.
Expenditure and Consumption: Use the formula: Expenditure = Rate * Consumption.

Featured Speakers/Sources

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