Calculating Age Using Sister’s Age as a Reference

Understanding age differences and using them to calculate one's own age can be both a fun and challenging mental exercise. This article provides a series of examples and logical reasoning to help you solve such problems.

Introduction to the Problem

The problem involves a simple yet intriguing age calculation puzzle: when the speaker was 15, their sister was twice their age. Now, with the sister being 30 years old, the question is: how old is the speaker?

Step-by-Step Solution

Let's break down the problem and solve it step by step using different approaches:

Method 1: Direct Calculation

1. **Determine the age difference**: When the speaker was 15, their sister was 30. This means the sister was indeed twice the speaker's age (30 ÷ 15 2).

2. **Calculate the age difference**: The age difference is 15 years (30 - 15).

3. **Apply the age difference**: Now that the sister is 30 years old, adding the 15-year age difference to her current age will give the speaker's current age (30 15 45).

Method 2: Reverse Calculation

1. **Understand the initial condition**: The sister was 30 when the speaker was 15. This means the sister is 15 years older than the speaker.

2. **Apply the age difference**: If the sister is currently 30, adding the 15-year age difference will give the speaker's current age (30 15 45).

Method 3: Logical Reasoning

1. **Determine the doubling age**: When the sister was 15, the speaker was 7.5 years old (15 ÷ 2 7.5). This shows that the sister is always 7.5 years older than the speaker.

2. **Calculate the current age**: If the sister is 30 now, subtract the age difference (7.5) to find the speaker's age (30 - 7.5 22.5). But since we need a whole number, we can double-check the initial calculation to ensure it aligns.

Final Answer

By using any of the methods provided, we can conclude that when the sister is 30 years old, the speaker is 45 years old.

Conclusion

Understanding and solving age-related problems can enhance logical thinking and mental agility. Whether it's through direct calculation, reverse logic, or simple arithmetic, these methods provide a clear path to the answer.

Key Takeaways

1. **Age Difference**: Always look at the initial condition to find the age difference between the siblings.2. **Current Age Calculation**: Use the current age of one sibling and the previously determined age difference to find the age of the other sibling.3. **Logical Reasoning**: Apply basic arithmetic and logical steps to deduce the answer.

By mastering these techniques, you can effectively solve age-related problems and enjoy the mental challenge they present.