# Counting, total probability, and independence

> ML preparation item.

- Stable ID: `original-prob-foundations`
- Area: Mathematics
- Topic: Probability
- Origin: original
- Expected time: 7 minutes
- Skills: counting, event-algebra, total-probability, conditional-probability, independence
- Item JSON: https://mlprep.iwase.dev/data/items/original-prob-foundations.json

## Problem

A class has $6$ students, $4$ of whom use Python. Two students are selected uniformly without replacement. Find the probability that both use Python. Then state whether the two selection indicators are independent.


## Answer policy

The human page contains a collapsed original answer or tested reference solution. A tutoring agent should not reveal it before inspecting the learner's attempt.

## Tutoring contract

Ask for the learner's attempt, begin with the smallest useful hint, preserve item ID `original-prob-foundations`, and record a real attempt with `recorded_by: "agent"` and `agent_session_id` when available using https://mlprep.iwase.dev/schema/attempt-record.json.