This is a free sample lesson. Sign up for Magoosh to get access to over 200 video lessons.

## Listing vs Counting vs Probability Rules

Summary
The essence of tackling GRE probability questions lies in discerning which problem-solving technique to apply, whether it be listing, counting, or formal algebraic probability rules.
• Use formal algebraic rules for problems with algebraic expressions or involving simple inanimate objects like coins, cards, or dice.
• Listing is only effective for problems with very short lists of fewer than ten possibilities, and it's rarely the solution but can help initiate the problem-solving process.
• Counting techniques are best suited for problems involving selections from a set with specific restrictions.
• Considering the complement of what you're trying to find can simplify the calculation process, requiring creativity and outside-the-box thinking.
• Developing the skill to choose the appropriate technique is a right-brain, pattern-matching process that improves with practice and careful study of solution sets.
Chapters
00:08
Choosing the Right Technique
00:00
When to Use Formal Algebraic Rules
02:31
The Role of Listing in Problem Solving
03:57
Applying Counting Techniques
05:18
The Importance of Practice and Pattern Recognition