Discrete random variables
This module covers core properties of discrete random variables, their probability distributions, and the calculation of expectation and variance, a found…
📖Study Guide
In-depth bilingual notes with worked past paper examples.
✍️Practice Exam
Original questions for this topic: MCQ + FRQ + Application + drag/match.
🎴Flashcards
20+ flashcards: definitions / formulas / pitfalls. Click to flip.
📊Exam Insight
How this topic is distributed across past papers — data that shows what matters.
How often is this tested?
Tested 67 times in the last 10 years — 14.8% of all S1 past-paper questions (67 of 438).
Most often tested as Probability distribution table.
Based on OwlsPrep's analysis of official CIE 9709 past papers (2016–2025).
📊 Which Mathematics topics are most tested? See the real past-paper frequency →
Stuck on a specific question?
Snap a photo or paste your problem — Ollie (our AI tutor) walks through it step-by-step with diagrams.
Try Ollie free →
Snap a photo or paste your problem — Ollie (our AI tutor) walks through it step-by-step with diagrams.
Try Ollie free →