Master percentage calculations in DI contexts: percent change, percent of total, successive percentages, and base value recovery.
Master percentage calculations in DI contexts: percent change, percent of total, successive percentages, and base value recovery.
Review the core rule: % change = (New − Old) / Old × 100
Always verify axis labels and legends before extracting values.
Check units on every axis before computing ratios or changes.
GI data requires interpolation — use approximate values and pick the closest answer.
Reverse %: divide by (1 + rate) — always identify what you're dividing by.
If group sizes differ, compute weighted average, not simple mean.
One counterexample makes a universal statement False.
Conclusions are limited to the data range provided, not broader populations.
Absolute change ($) and relative change (%) answer different questions.
P(at least one) = 1 − P(none). In set logic, use complement for "not" conditions.
A product price increased from $80 to $100. Percentage increase = ?
After a 20% increase, a salary is $60,000. Original salary = ?
A product increased 10% in January, then decreased 10% in February. Net change from start:
Market share went from 15% to 18%. Percentage POINT change and relative % change are:
A chart shows revenue grew 15% from Year 1 to Year 2 and 20% from Year 2 to Year 3. Overall growth from Year 1 to Year 3 = ?
A store discounts an item 25%, then adds 10% tax. If original price = $80, final price = ?
A pie chart shows Division A has 35% of revenue. Total revenue is $400M. Division A contributes:
In a table, Column A shows values indexed to Year 1 = 100. Year 3 = 125. This means Year 3 is:
Revenue grew by $30M, which represents a 15% increase. Original revenue = ?
Cost of goods fell 8%, saving $24,000. Original cost of goods = ?
Use the ORIGINAL as denominator, not the new value.
To find the original before a 25% increase: divide by 1.25.
A 20% increase then a 10% increase = ×1.20 × 1.10 = ×1.32, not 30%.
Always identify the correct "whole" before dividing.