Maths · GCSE · Probability

Conditional probability

gcse-math-p9Free7:01Heddy Score 1 of 7, below the standard

Plays from youtube-nocookie.com. No YouTube cookies until you press play.

What you need to know

  • Conditional probability is the chance of one event given another has happened.
  • The given condition reduces the set of outcomes considered.
  • Two-way tables, trees and Venn diagrams can all show it.

In this clip

17:20–21:17Recurring decimals to fractionsmh7
49:10–59:52Prime factorisationm26
59:52–74:23Calculating in standard formm48
83:13–91:41Compound interestmh12
91:41–93:46Reverse percentagesm52
125:33–130:33Upper and lower bounds in calculationsgcse-math-n16b
130:33–143:52Surds: exact rootsmh4
146:41–152:32Angles in polygonsm16
152:32–155:52Angles in parallel linesm123
155:52–164:27Bearingsm134
184:14–191:39Density and pressuregcse-math-r11b
234:23–240:15Pythagoras and trigonometry in 3Dgcse-math-g20d
240:15–256:21The sine rulegcse-math-g22a
280:34–290:46Circle theorems: anglesgcse-math-g10a
294:34–305:17Vector proofsgcse-math-g25b
317:30–333:04Factorising harder quadraticsgcse-math-a4f
342:47–346:21The quadratic formulagcse-math-a18e
346:21–350:03Completing the squaregcse-math-a18d
354:37–372:23Algebraic fractionsgcse-math-a4g
400:13–417:32Simultaneous equationsm19
418:28–422:36Tangent to a circlegcse-math-a16b
468:31–473:47Transforming graphsgcse-math-a13
489:04–494:47Quadratic inequalities and set notationgcse-math-a22c
494:47–502:33Iterationgcse-math-a20
509:25–513:07nth term of a quadratic sequencegcse-math-a25b
516:32–520:51Algebraic proofgcse-math-a6c
561:50–564:24Box plotsgcse-math-s4c
564:24–584:36Histogramsgcse-math-s3a
594:37–601:38Conditional probabilitygcse-math-p9
607:21–612:43Sampling & biasmh18
Also coversSignificant figuresm43
Also coversEstimating before calculatingm32
Also coversBest-buy comparisonsm95
Also coversHCF & LCM by prime factorsm54
Also coversError intervalsmh5
Also coversLocigcse-math-g2c
Also coversArcs & sectorsmh14
Also coversComposite solids and frustumsgcse-math-g17d
Also coversArea of any trianglegcse-math-g23
Also coversGeometric proofgcse-math-g6
Also coversPerpendicular linesgcse-math-a9d
Also coversArea under a graphgcse-math-a15b
Also coversThe cosine rulegcse-math-g22b
Also coversTree diagramsmh17
Also coversCumulative frequency graphsgcse-math-s3b
Heddy Score1/7, Below the standard
  • Trusted source · passed. The creator's own upload, live and playable here.
  • On the map · not judged yet. A teacher watched it: it mainly teaches this map topic.
  • Spec-true · not judged yet. Accurate, and right for the current UK specification.
  • Focused · failed. One idea, short enough to watch in one go.
  • Accessible · not judged yet. Good captions, clear sound and pictures.
  • Safe for children · not judged yet. Right for 11 to 16 year olds, with no sales pitch.
  • Proven · not judged yet. Earned from our students: they learn from it, find it helpful and watch it to the end.
★ passed · ☆ pending · ✕ failed
Our students

Not enough students yet

Our own students' answers. These are what move ★7 Proven.
How the Heddy Score works

Why we picked it

Corbettmaths' ten-hour Higher course recap spending a few minutes per topic; best used chapter by chapter by Year 11 Higher students.

corbettmaths on YouTubechecked 2026-10-16