Mathematics Cumulative frequency

The number of houses in each village in Essex were counted The cumulative frequency is found by adding up as you go along (a running total) Cumulative frequency curves The number of houses in each village in Essex were counted No. of houses No. of villages 50 < P < 100 7 100 < P < 150 24 150 < P < 200 29 200 < P < 250 18 250 < P < 300 12 Cumulative freq. Step 1 Work out cumulative frequencies 7 31 Step 2 Write down the co-ordinates you are going to plot 60 78 90 Step 3 Draw the cumulative frequency curve Co-ordinates: (50, 0) , (100, 7) , (150, 31) , (200, 60) , (250, 78) , (300, 90) The graph will need the Cumulative Frequency on the y-axis 0  90 and No. of houses on the x-axis 0  300 All points must be joined using a smooth curve

Cumulative frequency curves From your curve calculate the : Median Lower quartile Upper quartile Inter quartile range No. of villages with more than 260 houses in 90 80 70 60 50 40 20 30 10 100 150 200 250 300 c.f. No. of houses 100th percentile UQ Median LQ Answers: Median = 175 houses LQ = 140 houses UQ = 215 houses IQR = 215 – 140 = 75 houses >260 hs = 9 villages 140 175 215