The idea in brief. The whole circle is one whole. Write each sector as a fraction of it, and the sector nobody labelled is whatever is left over when the others are taken away from 1.
Lesson video, with the working
Reading fractions from a pie chart
4 min 13 s
The film teaches 2 questions in turn. Each question shows first; its working is written as the film explains it.
The pie chart shows the number of cartons of milk a school canteen sold in a week. The canteen sold 240 cartons altogether. The part representing plain milk is marked with a right angle.
(a) How many cartons of plain milk were sold?
(b) What fraction of the cartons were banana milk? Give your answer in its simplest form.
from the pie chart, 96 of the cartons were chocolate milk and 54 were strawberry milk
the right angle shows that 1/4 of the cartons were plain milk
plain milk = 240 ÷ 4 = 60
banana milk = 240 − 60 − 96 − 54 = 30
fraction of banana milk = 30/240 = 1/8
Ans: (a) 60 (b) 1/8
Example 1
The pie chart shows the number of pupils at a holiday camp who chose each of four workshops. 200 pupils chose a workshop altogether. The part representing the baking workshop is one half of the chart, the part representing the robotics workshop is marked with a right angle, and 30 pupils chose the batik workshop.
(a) How many pupils chose the origami workshop?
(b) What fraction of the pupils chose the origami workshop? Give your answer in its simplest form.
from the pie chart, 30 pupils chose the batik workshop
the pie chart is cut into halves, so 1/2 of the pupils chose the baking workshop
baking = 200 ÷ 2 = 100
the right angle shows that 1/4 of the pupils chose the robotics workshop
robotics = 200 ÷ 4 = 50
origami = 200 − 100 − 50 − 30 = 20
fraction for origami = 20/200 = 1/10
Ans: (a) 20 (b) 1/10
How to solve it
Read the whole and the labelled parts. A right-angle mark shows one quarter of the whole circle.
Find plain milk: 240 divided by 4 is 60 cartons.
Subtract every known part: 240 minus 60 minus 96 minus 54 is 30 banana milk cartons.
Write the fraction as 30 over 240, then simplify it to one eighth.
For the workshop chart, find the half and quarter first: 200 divided by 2 is 100; 200 divided by 4 is 50.
Origami is 200 minus 100 minus 50 minus 30, which is 20 pupils. The fraction 20 over 200 simplifies to one tenth.
Read the half and quarter first. Subtract every known part, then simplify the fraction.
Practice questions with worked solutions
Question 1 is free to try. The other 7 open in the free trial, each with its full working.
Question 1 of 8 · Basic · free to tryThe pie chart shows the number of books of each kind on a shelf in the…The pie chart shows the number…
The pie chart shows the number of books of each kind on a shelf in the school library. There are 60 books on the shelf altogether.
(a) How many puzzle books are on the shelf?
(b) What fraction of the books on the shelf are puzzle books? Give your answer in its simplest form.
What should my child understand when reading pie charts?
Every sector in a pie chart represents part of the same complete collection.
What your child learns here
Every sector in a pie chart represents part of the same complete collection. Your child reads the title and category labels to identify that whole, then uses the supplied fractions or markings to describe its parts. This subtopic follows the MOE Primary 4 outcome on reading and interpreting pie charts. It connects the size of a sector to its share of the collection without assuming that its count is known.
Use the chart title to identify the complete group and the labels or key to match each sector to its category.
Compare sector sizes within one chart to compare the numbers in its categories, since all sectors share the same whole.
Recognise one half from a diameter and one quarter from a right angle at the centre when those features are established by the diagram.
Find an unknown fraction by subtracting the known, non-overlapping sectors' combined share from one whole.
Distinguish information about a category's fraction from its actual count, which needs a total or another numerical relationship.
Does the answer make sense?
After finding an unknown sector fraction, your child can add all the separate sector fractions. They must total exactly 1 because the sectors together represent the entire collection, with no category counted twice.
How to practise these questions
Basic questions identify a largest group or find a missing fraction and count from a pie chart. Intermediate work matches sectors to a table or bar graph, calculates a fraction of a total and uses right-angle markings to establish quarter shares. Challenge questions compare a sector with a quarter and a half, or judge a statement about two stalls with equal totals. Ask your child to state what the whole circle counts before connecting its parts to numbers elsewhere in the question. Matching labels and categories comes before any addition or comparison. If those connections need support, members can view the solution film after an attempt. The free library-books question includes written working for finding the puzzle-book count and its fraction of the shelf total, so you can connect a sector with both a number and a share.
Questions parents ask
Does a larger pie chart sector always mean more people? Within the same chart, a larger sector represents more of the collection, assuming each person is counted in one category. Across two charts with different totals, sector size alone is insufficient. A larger fraction of a smaller group can still represent fewer people.
Can my child tell a sector's fraction just by looking at it? An exact fraction needs information that supports it, such as a label, equal-sector markings, a diameter or a marked right angle at the centre. The apparent size can help with a rough comparison, but your child should explain an exact answer from the given information.
Should my child use percentages to read a P4 pie chart? Fractions provide the approach for these Primary 4 questions. The P4 statistics outcome names reading and interpreting pie charts, while percentage is introduced in the Primary 5 number syllabus. Your child can identify the whole and its fractional parts without changing them into percentages.
