IGCSE›Cambridge IGCSE Maths›Mind mapsBasic ProbabilityCambridge IGCSE Maths: Mind mapStudy pack PDFAlso for this subtopic:Revision notesFlashcardsSubtopic testCover factsThe scale0 means impossible1 means certain0.5 means equally likely either wayWrite as fractions, decimals or percentagesSingle eventP=favourable outcomestotal outcomesP = \frac{\text{favourable outcomes}}{\text{total outcomes}}P=total outcomesfavourable outcomesNeeds equally likely outcomesFair die: P(4)=16P(4) = \frac{1}{6}P(4)=615 red, 3 blue: P(blue)=38P(\text{blue}) = \frac{3}{8}P(blue)=83Probabilitybasic ideas00.51ComplementP(not event)=1−P(event)P(\text{not event}) = 1 - P(\text{event})P(not event)=1−P(event)Extended notation: P(A′)=1−P(A)P(A') = 1 - P(A)P(A′)=1−P(A)P(rain)=0.3P(\text{rain}) = 0.3P(rain)=0.3 gives P(no rain)=P(\text{no rain}) =P(no rain)= 0.7Fair, biased, randomFair: every outcome equally likelyBiased: outcomes not equally likelyRandom: outcome cannot be predicted in advanceAll probabilities in the sample space sum to 1Exam tipsAnswer must lie between 0 and 1Outside that range means an arithmetic errorBiased die: use the given probabilities, not 16\frac{1}{6}61Give the simplest form