LEARN · EXPLAIN · REVISE

From m people, form a 3-person committee that includes a specified person.

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

TOPIC 01

Counting principles: mixed review

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 / Standard#Your turn

m=10

Counts use nonnegative integer sizes; decide whether labels, order and rotations distinguish outcomes.

Skills and prerequisite lessons

Working and explanation

BUILD THE REASONING

Hint 1

Decide whether choices are alternative cases or successive stages, then check overlap.

Hint 2

Use this intermediate relation.

C_{m-1}^2

Worked solution

Decide whether choices are alternative cases or successive stages, then check overlap.
Apply the stated relation and retain its conditions.
$N=C_{9}^2=36$
Select only the remaining two members from the other people.

The requested value is 36.

Checks and common pitfalls: Select only the remaining two members from the other people.

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

Teacher preparation and assessment