Interpret two-way tables
Theory
A two-way table sorts data by two things at once, such as class and activity. Each cell counts the data that fits its row and its column, and the totals add along rows and down columns. This Year 6 maths page shows how to read a two-way table, use its totals, find missing values and compare groups.
A two-way table has one feature across the top (the columns) and another down the side (the rows).
A cell is where a row and a column meet. In the first diagram, the cell for 6B and Music is \(11\): \(11\) students in 6B chose music.
A row total adds across a row; a column total adds down a column. The grand total (bottom right) counts everyone.
The row totals and the column totals both add to the grand total, because both count every person once.
Two-way table rules:
How to read a two-way table
- Find the row for the first feature (for example, the class).
- Move across to the column for the second feature (for example, the activity).
- Read the cell. For "altogether", use a total.
How to find a missing value
- Choose a row or column with only one missing cell.
- Subtract the cells you know from that row or column total.
- Check that every row and column now adds up.
Row 6B, column Music: \(11\) students.
| \(13 + 6 + 10\) | \(=\) | \(29\) |
\(29\) students (the 6A row total).
| \(13 + 8\) | \(=\) | \(21\) |
\(21\) students.
| \(29 + 25\) | \(=\) | \(54\) |
| \(21 + 17 + 16\) | \(=\) | \(54\) |
\(54\) students both ways.
(ii) Which activity was chosen by the most students?
| \(13 - 8\) | \(=\) | \(5\) |
(i) \(5\)
(ii) Sport (\(21\) students)
(i) How many students wore a hat?
(ii) How many students are in the table?
| \(17 + 14\) | \(=\) | \(31\) |
| \(22 + 22\) | \(=\) | \(44\) |
(i) \(31\)
(ii) \(44\)
(i) How many Juniors bought lunch at the canteen?
(ii) How many Seniors brought lunch from home?
| \(46 - 34\) | \(=\) | \(12\) |
| \(41 - 15\) | \(=\) | \(26\) |
(i) \(12\)
(ii) \(26\). Check: \(34 + 26 = 60\) and \(12 + 15 = 27\).
| \(46 + 41\) | \(=\) | \(87\) |
| \(60 + 27\) | \(=\) | \(87\) |
Down the Total column: \(87\). Along the Total row: \(87\). Both ways give \(87\).
\(21\) is in the Total row, so it counts 6A and 6B together. The 6A sport cell is \(13\).
Common pitfalls
Frequently asked questions
What is a two-way table?
A table that sorts data by two features at once, one across the top and one down the side.
What is the grand total?
The number in the bottom right corner: everyone in the table.
How do I find a missing number?
Subtract the numbers you know from the total of that row or column.
What does a cell show?
The count that fits both its row and its column.
How do I compare two groups?
Read the two cells in the same column and subtract to find the difference.