MONEY & FINANCE · TEXTBOOK LESSON
Everyday mathematics uses arithmetic, percentages, rates and units to make informed decisions. The key is to model the situation correctly before calculating.
Learning objectives
By the end of this lesson, you should be able to:
- Identify the quantities and units in a real-world problem.
- Select the correct arithmetic, percentage or rate relationship.
- Carry out calculations with appropriate accuracy.
- Interpret the numerical result in practical terms.
1. Key vocabulary and definition
Definition
A rate compares two quantities with different units, such as kilometres per hour or AED per kilogram. Real-world calculations must keep units consistent.
rateunitpercentagecostestimateconversion
2. Essential facts and rules
These are the facts you should know before attempting the worked example.
Key mathematical facts
- Always convert units before combining quantities.
- Percentage change is measured relative to the original value.
- For compound growth, repeated percentage changes multiply rather than simply add.
3. Standard method
A reliable method helps prevent errors and makes your reasoning easy to follow.
1
Write down the known quantities with units.
2
Convert to compatible units.
3
Choose the relevant formula or unit rate.
4
Calculate and round appropriately, usually at the end.
5
Interpret whether the result is affordable, feasible or reasonable in context.
4. Worked example
Worked example
A car travels 360 km using 30 L of fuel. Find its fuel economy in km/L.
1
Fuel economy = distance ÷ fuel used.
2
360 ÷ 30 = 12.
3
The unit is kilometres per litre.
4
Fuel economy = 12 km/L.
5. Common mistakes
Watch out for these
- Starting calculations before deciding what the question is asking.
- Skipping important steps or changing notation midway through a solution.
- Accepting an answer without checking whether its size, sign or unit is sensible.
6. Video lesson
This topic is ready for a matching video lesson. The written textbook lesson is fully available now; additional videos can be added to the same lesson template.
7. Practice exercise
Complete these without looking at the answers first.
- Convert 2.5 kg to grams.
- An item costing 200 AED increases by 8%. Find the new price.
- A vehicle travels 150 km in 2.5 h. Find average speed.
- A recipe for 4 people uses 300 g flour. How much is needed for 10 people?
- A bill of 480 AED is shared equally by 6 people. How much each?
Show answers
- 2500 g
- 216 AED
- 60 km/h
- 750 g
- 80 AED
8. Chapter summary
- Understand the underlying idea before memorising a procedure.
- Use precise mathematical notation and show a logical method.
- Always check the final result.