Foundation

USE WHEN
A long word problem mixes percentages with ratios, averages, work, speed, composition or budgets and hides the main equation.
BEST METHOD
Invariant Mapping
TARGET
90–120 sec
MASTERY
not started
A long word problem mixes percentages with ratios, averages, work, speed, composition or budgets and hides the main equation.
Identify invariants and constraints first, normalize intelligently, then connect multipliers instead of solving every intermediate quantity.
Ask: What stays constant? What is the base of each percentage? Which quantities are multiplicative?
First identify what stays constant—budget, work, total, or distance—then write the percentage equation.
Timed drill
Identify the base or invariant before you calculate.
Attempt first · Standard Example
Attempt first · CAT-Level Example
3-level practice ladder
Foundation
CAT Standard
Advanced / Hybrid
cat 2023 slot 3 fruit-stock percentage constraints and cat 2024 slot 3 boys/girls activity percentages are strong multi-constraint examples.