Aptitude Topics
Successive Percentage
When a value is altered by a certain percentage and the resulting value is modified again by another percentage, it is termed a successive change.
Fundamental Principles
Effective Percentage Change Formula
For consecutive changes of a% and b%, the effective total change is given by: a + b + (ab / 100).
Essential Formulation Tips
- Use a positive sign for increases and a negative sign for decreases in the compound formula.
Shortcut Execution Techniques
- If a price is increased by x% and then decreased by x%, there is always a net decrease of (x² / 100)%.
Contextual Inquiries (FAQs)
Q: Does the order of successive percentage changes matter?
A:
Example Breakdown: Consecutive Changes
Counter-intuitive concept frequently featured in competitive trick entries.Problem QueryA salary is increased by 10% and then decreased by 10%. Find the net change percentage.
Step-By-Step Solution Path
Using formula with a = 10, b = -10:
Net = 10 + (-10) + (10 × -10 / 100)
= 0 - 1 = -1%
There is a net decrease of 1%.
Analytical Hint: Remember that a reduction uses a negative value.
Successive Problems Set 1
Testing compounding rules on prices and dimensions.
Q1. The price of a car is raised by 20% and then reduced by 30%. What is the net percentage effect?