A student asks when calculating percentages is useful in real life. What is the most appropriate example to illustrate this?

Calculating percentages is particularly useful in real life when it comes to understanding discounts and sales, making option D a strong example. When a mother goes shopping during a store sale, she often encounters price reductions that are expressed as percentages. For instance, if an item originally costs $100 and is on sale for 30% off, she needs to calculate what the discount amounts to and what the final price will be after applying that discount. This real-world application of percentage calculation helps consumers make informed decisions about their purchases and manage their budgets effectively.

The other examples, while relevant to various professions, do not emphasize percentage calculations as directly as shopping does. A builder cutting materials and an architect designing a building may involve measurements and calculations, but these may not specifically highlight the concept of percentages as clearly as calculating sale prices. Similarly, a pharmacist measuring medication does require precision, but it typically involves volumes and weights rather than percentage calculations. Thus, the shopping scenario directly illustrates the practical use of percentage calculations in everyday life.