E7b — AQA GCSE Statistics
Test yourself on E7b with AQA GCSE practice questions.
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Your focus
- Calculate and interpret rates of change over time from tables using context specific formula.
E7b exam tips
Quick Revision Summary (Key Takeaway)
E7b in AQA GCSE Statistics covers box plots (box-and-whisker diagrams), which visually summarise a distribution using the minimum, lower quartile, median, upper quartile and maximum. Students must construct box plots from data or cumulative frequency graphs and interpret them to compare distributions using medians and interquartile ranges, including identifying outliers.
How Students Lose Marks (Examiner Pitfalls)
Pitfall: Confusing the box with the full range or drawing whiskers to the quartiles instead of the extremes.
❌ Weak Answer (Loses Marks):Draws a box from the minimum to the maximum value, with the median line in the middle, and labels the ends as quartiles.
Example improved answer:Draws a box from the lower quartile to the upper quartile, with a line at the median. Whiskers extend to the minimum and maximum values that are not outliers. Outliers are plotted as separate crosses beyond the whiskers.
Examiner Tip: Always label the five key values on your diagram: minimum, LQ, median, UQ, maximum. This shows the examiner you know what each part represents.
Pitfall: Using n/2 to find quartiles or misreading positions on a cumulative frequency graph.
❌ Weak Answer (Loses Marks):For a data set of 20 values, finds the lower quartile at the 10th value instead of the 5th value.
Example improved answer:For n values, the lower quartile is at position n/4, the median at n/2, and the upper quartile at 3n/4. On a cumulative frequency graph, read across from these positions on the cumulative frequency axis to the curve, then down to the value axis.
Examiner Tip: Check whether you are working with raw data or a cumulative frequency graph; the position formulas are the same but the reading method differs.