Min-Max Problems (GMAT Focus) - Master Summary
Before solving, always check:
Must values be integers?
Is zero allowed?
Can values repeat?
Are negative values allowed?
Are values required to be distinct?
These restrictions often determine the entire solution.
Four Standard Min-Max Moves
To maximize the largest value:
→ Minimize all other values.
To minimize the largest value:
→ Maximize all other values.
To maximize the smallest value:
→ Make values as equal as possible.
To minimize the smallest value:
→ Push value away from the others as much as allowed.
Always determine whether decimals/fractions are allowed.
Zero is often the smallest legal value.
If zero is allowed:
• Maximum values often increase
• Minimum values often decrease
Set-Based Min-Max
For two sets:
Maximum overlap
= Smaller set
Minimum overlap
= A + B − Total
(if positive, otherwise 0)
Formula:
A ∪ B = A + B − A∩B
Three-Set Venn Diagram Rules
Maximum triple overlap
= Smallest set
Minimum triple overlap
= A + B + C − 2(Total)
(if positive, otherwise 0)
For percentages:
Minimum triple overlap
= A + B + C − 200
(if positive, otherwise 0)