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Cumulative frequency diagrams show running totals and are used to estimate the median, quartiles and interquartile range. Students draw the characteristic S-shaped curve and read off values at key percentile positions.
Students make these errors again and again. Knowing them in advance gives you a head start.
Plotting cumulative frequency at the midpoint instead of the upper class boundary
Joining points with straight lines instead of a smooth curve
Reading the median from the wrong axis on the graph
Insights pulled from Cambridge IGCSE (0580) examiner reports — the exact mistakes candidates make every year.
In probability without replacement, the denominator DECREASES by 1 for each subsequent pick (13 → 12 → 11...). Getting 104/169 instead of the correct answer usually means you forgot this.
“There were very few candidates who did not recognise the significance of the lack of replacement of the first counter, although where this was an issue some still gained credit for an answer of 104/169 with others compounding their error by missing some of the required pairs.”
Source: CIE 0580 · June 2024 · Paper 2 · Q25
For 'exactly one green button' out of two picks, there are TWO orderings: green-then-not OR not-then-green. Calculate one product and DOUBLE it (or add both products).
“Most recognised the need to start off with 5/13 for the probability of a first button being green, which earned a first method mark. Many fewer were able to use this correctly in a product with 8/12 for a second button being non-green to score the next mark. Only the stronger candidates realised that they also needed to double the result of the product to account for the possibility of green being the second button.”
Source: CIE 0580 · November 2023 · Paper 4 · Q15
In a histogram, bar HEIGHT = frequency density (frequency ÷ class width). Find the scale using a bar whose frequency AND width you know, then apply it to the others.
“This proved challenging for many. Those answers displaying understanding that the heights of the blocks of a histogram represented the frequency densities usually had no difficulty. Some clearly showed the calculation of the scale factor for the first bar as 17.2 ÷ 0.86 = 20 and used this correctly with the remaining frequency densities.”
Source: CIE 0580 · June 2022 · Paper 4 · Q5b
Based on 3of 510+ insights extracted from CIE 0580 examiner reports (2018–2024).
This topic is tested by the following exam boards. Our AI tutor covers each one with board-specific content.
Box plots (box-and-whisker diagrams) display the five-number summary of a dataset and are ideal for comparing distributions. Students draw, interpret and compare box plots, calculating the interquartile range and identifying skewness.
Frequency tables organise raw data into categories or class intervals for analysis. Students must construct tables, calculate totals, and use them to find averages and draw statistical diagrams.
Histograms display continuous grouped data using bars whose area (not height) represents frequency. This higher-tier topic requires students to calculate frequency density and interpret histograms with unequal class widths.
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