IGCSE›Cambridge IGCSE Maths›Mind mapsAverages & RangeCambridge IGCSE Maths: Mind mapStudy pack PDFAlso for this subtopic:Revision notesFlashcardsSubtopic testCover factsThree averagesMean: sum of values ÷ number of valuesMedian: middle value of ordered dataMode: most frequent valueEven count: average the two middle valuesWhich to useMean uses every value but outliers affect itMedian is unaffected by outliersMode works for non-numerical dataRangeRange = highest − lowestMeasures spread, not averageSmall range means clustered dataAveragesand rangemeanmedianmodeFrequency tablesMode is the value with the highest frequencyMedian position is n+12\frac{n+1}{2}2n+1mean=∑(value×frequency)∑frequency\text{mean}=\frac{\sum(\text{value}\times\text{frequency})}{\sum\text{frequency}}mean=∑frequency∑(value×frequency)2,3,4,5 with 3,5,4,2: mean =4714≈3.36=\frac{47}{14}\approx 3.36=1447≈3.36ExtendedQ1 and Q3 are quarter and three-quarter pointsIQR=Q3−Q1\text{IQR}=Q3-Q1IQR=Q3−Q1, the middle 50%Grouped mean uses class midpointsModal class has the highest frequencyExam tipsOrder the data before finding the medianWrite estimate for a grouped meanIQR is less affected by outliers than range