Foundation and Higher · tables and diagrams
Two-way tables.
Every row and
column must add up.
start where there is
one gap
a table that sorts data two ways —
Two-way
rows one way, columns the other
the totals tie it together
step 1 of 4
Start with one gap
1. Year 10 row: 30 − 12 = 18.
2. Walk column: 20 − 12 = 8.
✓ One gap in a line? You can fill it
| Walk | Bus | Total |
|---|
| Year 10 | 12 | 18 | 30 |
|---|
| Year 11 | 8 | | |
|---|
| Total | 20 | | 50 |
|---|
step 2 of 4
Totals must agree
1. Total column: 50 − 30 = 20.
2. Bus total: 50 − 20 = 30. Then 30 − 18.
✓ Check: 8 + 12 = 20
| Walk | Bus | Total |
|---|
| Year 10 | 12 | 18 | 30 |
|---|
| Year 11 | 8 | 12 | 20 |
|---|
| Total | 20 | 30 | 50 |
|---|
step 3 of 4
Stem-and-leaf: the key
1. Stem: the tens. Leaf: the units.
2. So the data is 12, 15, 18, 20, 23, …
✓ Leaves must be in order
Key: 1 | 2 means 12
step 4 of 4
Averages from it
1. 9 values, so the median is the 5th.
2. Range: biggest minus smallest.
✓ Mode: 23, the repeated leaf
median = 23 · range = 34 − 12 = 22
tables and diagrams —
Two-way table
fill any line with one gap
Grand total
rows and columns both reach it
Stem-and-leaf
read the key, keep leaves in order
Probability from a table:
the cell ÷ the right total.
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