LEARN · EXPLAIN · REVISE

Disjoint events have probabilities 1/(k+3) and 2/(k+3). Find their union probability.

Read the idea, work independently, then explain what changed.

TOPIC 01

Probability: mixed assessment

A mixed assessment: identify the method, justify it and revise your reasoning.

Use one hint at a time. A correction explains what changed, not just the final answer.

01 / Foundation#Your turn

k=8

Skills and prerequisite lessons

Working and explanation

BUILD THE REASONING

Hint 1

Describe the sample space and event sets, then count or apply a probability identity.

Hint 2

Disjointness removes the overlap term.

Worked solution

Describe the sample space and event sets, then count or apply a probability identity.
Calculate or simplify this relation.
$P(A\cup B)=1/11+2/11=3/11$
Mutually exclusive does not mean independent.

The requested value is 0.27272727.

Checks and common pitfalls: Mutually exclusive does not mean independent.

Think first. Reveal a hint when the class is ready.

Teacher preparation and assessment