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IGCSE Maths: Statistics

Topic 9 of the Cambridge IGCSE Mathematics (0580) syllabus: from averages and charts to cumulative frequency and histograms. Here is what each part asks, a practice question for each, and the mistakes that cost the most marks.

Practise statistics as a game

The 7 parts of the topic

Each part with one practice question, made by the same engine your child plays. Parts marked Extended are for the Extended paper only.

9.1 Classifying statistical data

Which of these is categorical (not numbers) data?

  1. the length of a leaf
  2. the number of cars in a car park
  3. favourite colour
  4. shoe sizes
Show the answer

favourite colour. Discrete data is counted, so only certain values are possible. Continuous data is measured and can take any value in a range. Categorical data is words or groups, not numbers.

9.2 Interpreting statistical data: read and draw inferences from tables and diagrams, compare data sets, know the limits of a conclusion

Test scores.
Class A: mean 61, range 27.
Class B: mean 67, range 12.
Which class had the more CONSISTENT scores?

  1. It is impossible to tell
  2. Class B
  3. They are the same
  4. Class A
Show the answer

Class B. Consistent means close together, so compare the ranges: 12 is smaller, so Class B. The mean says nothing about how spread out the scores were.

9.3 Averages and spread: mean, median, mode, range, quartiles; estimated mean of grouped data

Find the interquartile range.
7, 11, 12, 16, 18, 21, 22

  1. 10
  2. 16
  3. 15
  4. 21
Show the answer

10. The median is the 4th value. The lower quartile is 11 and the upper quartile is 21. 21 − 11 = 10.

9.4 Statistical charts: bar, pie, pictogram, stem-and-leaf, frequency diagrams

A pie chart shows 90 people.
The sector for tea is 28°. How many chose tea?

  1. 25.2
  2. 83
  3. 28
  4. 7
Show the answer

7. 28° out of 360° is 7/90 of the people. 7/90 of 90 = 7.

9.5 Scatter diagrams, correlation and lines of best fit

What kind of correlation would you expect between
length of hair and salary?

  1. No correlation
  2. Positive correlation
  3. It cannot be known
  4. Negative correlation
Show the answer

No correlation. Neither has anything to do with the other: no correlation.

9.6 Cumulative frequency diagrams: median, quartiles, percentiles Extended

There are 100 values on a cumulative frequency graph.
Which position gives the 80th percentile?

  1. the 80th value
  2. the 20th value
  3. the 8th value
  4. the 78th value
Show the answer

the 80th value. The 80th percentile is 80% of the way through the data: 80% of 100 = 80. Read across from 80 on the cumulative frequency axis.

9.7 Histograms with unequal class widths Extended

A class in a histogram is 20 units wide
and has frequency 60.
What is its frequency density?

  1. 60
  2. 3
  3. 0.33
  4. 1200
Show the answer

3. Frequency density = frequency ÷ class width = 60 ÷ 20 = 3.

The mistakes that cost the most marks

Huh Lab checks every wrong answer against known mistakes like these, and goes back to the step behind the one your child keeps making.

Mixes up frequency and frequency density

In a histogram the AREA is the frequency. Density = frequency ÷ width.

Reads the angle as the number of people

The angle is a share of 360°. Turn it into a fraction of the whole first.

Gives the range instead of the interquartile range

The IQR ignores the ends: it is upper quartile minus lower quartile, the middle half.

Gives the probability of the OTHER outcome

Re-read which colour the question asks about.

Gives one class instead of the running total

Cumulative means added up so far: this class AND every class before it.

Uses 100 instead of 360

A pie chart is a full turn: fractions of 360°, not of 100.

Stretches a conclusion beyond the data

Ask who was actually asked. One class, one day or one website cannot speak for everyone.

Reads the frequency instead of the value

Half of the total tells you where to START on the side axis. The median is what you read off the bottom axis after going across and down.

Other IGCSE Maths topics

Number17 parts Algebra and graphs13 parts Coordinate geometry7 parts Geometry8 parts Mensuration5 parts Trigonometry6 parts Transformations and vectors4 parts Probability4 parts

Practise it as a game

Short rounds on any topic, a new question every time, the exact mistake found, and a report to you after every session.

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