Every card in Statistics, Year 8: pie charts, frequency tables and bar charts
The whole deck, in order — so you can read it through before your child ever sees it.
← Back to Statistics, Year 8: pie charts, frequency tables and bar charts
- A pie chart shows how 60 pupils travel to school. The 'walk' slice has an angle of 90°. How many pupils walk?
15
HintWhat fraction of a full turn is the slice?
Why90° is a quarter of 360°, and a quarter of 60 is 15.
- A slice of a pie chart has an angle of 72°. What fraction of the data does it show?
1/5
HintCompare the angle with a full turn.
Why72 ÷ 360 = 1/5, because 5 × 72 = 360. A slice is always its angle out of 360.
- Pie chart A shows that 50% of Class A like art; pie chart B shows that 50% of Class B like art. Can you say that the same number of pupils like art in each class?
No — not without the class totals
HintHalf of what, in each case?
WhyHalf of a class of 30 is 15, but half of a class of 20 is 10. Pie charts show proportions, so equal slices need not mean equal counts.
- A pie chart represents 120 people, and 30 of them chose tea. What angle should the tea slice have?
90°
HintEach person is worth the same number of degrees.
Why360 ÷ 120 = 3° per person, and 30 × 3 = 90°. Or notice that 30 out of 120 is a quarter of the circle.
- A frequency table shows score 1 (frequency 3), score 2 (frequency 5) and score 3 (frequency 2). What is the mode?
2
HintLook for the largest frequency, then read across.
WhyThe mode is the score that occurs most often. The highest frequency is 5, and it belongs to a score of 2.
- A frequency table shows score 1 (frequency 3), score 2 (frequency 5) and score 3 (frequency 2). What is the mean score?
1.9
HintMultiply each score by how often it occurs before adding.
WhyThe total score is 1 × 3 + 2 × 5 + 3 × 2 = 19, and there are 3 + 5 + 2 = 10 scores. 19 ÷ 10 = 1.9.
- A frequency table records 21 values in order. Which position holds the median? (number only)
11
HintIt is the middle one, with equal numbers either side.
Why(21 + 1) ÷ 2 = 11. The 11th value has ten values below it and ten above it.
- A frequency table shows score 0 (frequency 4), score 1 (frequency 3) and score 2 (frequency 4). What is the median score?
1
HintFind the position of the middle value, then count through the frequencies.
WhyThere are 11 values, so the median is the 6th. The first four are 0s, and the 5th, 6th and 7th are 1s.
- The classes in a table are 0 ≤ h < 10 and 10 ≤ h < 20. Which class does h = 10 go in?
10 ≤ h < 20
HintCheck which class includes its lower end.
WhyThe sign < 10 leaves 10 out of the first class; the sign 10 ≤ puts it in the second. Each value belongs to exactly one class.
- When data is put into a grouped frequency table, what information is lost?
The exact individual values
HintYou only know which class each one fell in.
WhyGrouping makes a long list easy to read and to chart, but you can no longer tell whether a value in 10 ≤ h < 20 was 10.1 or 19.9.
- Why are heights recorded in classes such as 140 ≤ h < 150 that leave no gaps between one class and the next?
Height is continuous, so any value must have a class
HintSomeone could be 149.9 cm tall.
WhyMeasured data can take any value. Classes such as 140–149 and 150–159 would leave a height of 149.5 with nowhere to go.
- A pupil groups 30 heights into classes with widths of 10 cm, 5 cm and 20 cm for a frequency table. What change would make the classes fair to compare?
Giving every class an equal width
HintA fair comparison needs boxes of one size.
WhyWith unequal classes, a wide class can look popular just because it is wide. Equal widths let the frequencies be compared directly.
- A chart shows two bars side by side for each month, one for 2023 and one for 2024. What type of chart is it?
A dual bar chart
HintIts name comes from the Latin for 'two', like 'duet'.
WhyPutting the two bars next to each other makes it easy to compare the two years month by month. It is also called a comparative bar chart.
- A chart stacks boys and girls in one bar for each club, so the full height of the bar shows the club's total. What type of chart is it?
A compound (stacked) bar chart
HintEach bar is built up from parts.
WhyIt shows totals clearly, and how each total is made up. It is also called a composite bar chart. The upper sections are harder to compare, as they do not start from a common line.
- What must a dual bar chart always include so that the reader knows which bar is which?
A key
HintIt unlocks the meaning of the colours.
WhyWithout it, two colours or shadings mean nothing. A chart also needs a title and labelled axes.
- You want to compare boys' and girls' scores in each subject directly. Which is better: a dual bar chart or a compound bar chart?
A dual bar chart
HintChoose the one where both bars start from the baseline.
WhySide-by-side bars begin at one level, so their heights can be compared at a glance. Stacked bars are better when the totals matter most.
1★ KS3-MATH-STA-0042
2★ KS3-MATH-STA-0043
3★ KS3-MATH-STA-0044
4★ KS3-MATH-STA-0045
5★ KS3-MATH-STA-0046
6★ KS3-MATH-STA-0047
7★ KS3-MATH-STA-0048
8★ KS3-MATH-STA-0049
9★ KS3-MATH-STA-0050
10★ KS3-MATH-STA-0051
11★ KS3-MATH-STA-0052
12★ KS3-MATH-STA-0053
13★ KS3-MATH-STA-0054
14★ KS3-MATH-STA-0055
15★ KS3-MATH-STA-0056
16★ KS3-MATH-STA-0057
Keep what you learn
Here, nothing is saved. In your child’s own sky every card is scheduled — it comes back just before they’d forget it — and the professor who wrote it is one tap away.