Solving word problems
Word problems about ratio and proportion can be solved with four simple steps: understand what is asked, plan how to find it, solve step by step, then check your answer. Reading the question slowly and picking out the numbers is the most important first step, because a small mistake there changes the whole answer.
Key idea
For sharing in a ratio: add the parts to get the total parts, find the value of one part, then multiply for each share.
Worked example
Worked example
A class of 30 pupils has boys and girls in the ratio 3 : 2. How many boys?
Understand: total 30, ratio 3 : 2.
Plan: total parts = 3 + 2 = 5.
Solve: one part = 30 ÷ 5 = 6, so boys = 3 × 6 = 18.
Check: girls = 2 × 6 = 12, and 18 + 12 = 30. ✓
Remember
- Add the parts to find total parts.
- One part = total ÷ total parts.
- Always check your answer adds back up.