Story problems with a ratio table
You learn to solve a word problem with a ratio table.
How to work it out
- Put what you know in the first column: one thing on top, the other underneath.
- Put what is asked for on top in the last column.
- Go via a step in between, often via 1: divide the top and the bottom by the same number.
- Then multiply the top and the bottom by the same number until you get there.
4
10
6
15
A worked example
4 kg of apples cost 6 pounds. How much do 10 kg cost?
- Put 4 kg and 6 pounds in the first column.
- Go to 1 kg: divide both by 4, so 6 ÷ 4 = 1.5 pounds.
- Then go to 10 kg: multiply both by 10, so 1.5 × 10 = 15.
- It costs 15 pounds.
More examples
In 3 packs there are 12 biscuits. How many biscuits are in 5 packs?
- Put 3 packs and 12 biscuits in the first column.
- Go to 1 pack: divide by 3, so 12 ÷ 3 = 4 biscuits.
- Then go to 5 packs: multiply by 5, so 4 × 5 = 20.
- There are 20 biscuits.
3
5
12
20
2 kg cost 5 pounds. How much do 6 kg cost?
- Put 2 kg and 5 pounds in the first column.
- Find the factor: 2 × 3 = 6, so times 3.
- Do the same underneath: 3 × 5 = 15.
- It costs 15 pounds.
2
6
5
15
Watch out
You mix up the numbers: pounds in the kilos row.
Give each row a name, like kg and pounds. A number always belongs in the row of its unit.
You multiply the amount asked for straight away by the price: 10 × 6 = 60 pounds.
6 pounds is the price of 4 kg, not of 1 kg. Go to 1 kg first.
Tips
- Write the unit next to each row, like kg and pounds.
Why it works
In this kind of story two things belong together, like kilos and pounds. In a table you see that straight away: one on top, the other underneath. With a step in between, often via 1, you work your way to what is asked.