Unit 9 · Class 9 IB MYP · Formula Sheet

Probability (Combined Events) Formulas — Class 9 IB MYP

Calculate probabilities of combined events using addition and multiplication rules.

Key Formulas

Independent Events

P(A \cap B) = P(A) \times P(B)

Mutually Exclusive

P(A \cup B) = P(A) + P(B)

General Addition

P(A \cup B) = P(A) + P(B) - P(A \cap B)

Conditional

P(A|B) = \dfrac{P(A \cap B)}{P(B)}

Worked Examples

1Using: Probability

A die is thrown. Find P(getting an even number).

Step 1: Even outcomes: {2, 4, 6} = 3.

Step 2: Total outcomes = 6.

Step 3: P = 3/6 = 1/2.

Answer: 1/2

Practice Now

Apply these formulas with 60+ practice questions and AI-powered doubt clearing.

Practice Now

More Class 9 IB MYP Formulas

Real Number SystemQuadratic ExpressionsCoordinate GeometryLinear & Non-Linear FunctionsCircle GeometryTrigonometry Introduction

Frequently Asked Questions

How many formulas are in Class 9 IB MYP Probability (Combined Events)?+
There are 4 formulas in the Probability (Combined Events) chapter for Class 9 IB MYP. Each formula is essential for solving problems in this topic.
How to remember Probability (Combined Events) formulas easily?+
Practice regularly with worked examples, group related formulas together, and use SparkEd's interactive practice mode to reinforce your memory through problem-solving.
Are these Probability (Combined Events) formulas enough for exams?+
Yes, these formulas cover the complete IB MYP Class 9 syllabus for Probability (Combined Events). Practice applying them to different types of questions for full exam readiness.

Master Probability (Combined Events) on SparkEd

Go beyond formulas. Practice at three difficulty levels with instant feedback, step-by-step solutions, and an AI coach.

Start Practising Free

SparkEd Maths provides free formula sheets for Class 1-10 across 7 education boards. All formulas are aligned to the 2025-26 syllabus.