Brian is 8 and his brother is twice his age. How old will his brother be when Brian is 11?
A 19
B 20
C 21
D 22
The Correct Answer and Explanation is :
To determine how old Brian’s brother will be when Brian is 11, let’s break down the information given:
- Current Ages: Brian is currently 8 years old, and his brother is twice his age. Therefore, we can calculate his brother’s current age as follows:
[
\text{Brother’s age} = 2 \times \text{Brian’s age} = 2 \times 8 = 16 \text{ years old}
] - Future Age Calculation: We need to find out how old Brian’s brother will be when Brian turns 11. The difference in their ages remains constant over time. Since Brian is currently 8 and will be 11 in 3 years, we can find his brother’s future age by adding the same amount of time (3 years) to his brother’s current age.
- Calculating Brother’s Age in 3 Years:
[
\text{Brother’s future age} = \text{Brother’s current age} + 3 \text{ years} = 16 + 3 = 19 \text{ years old}
]
So when Brian is 11, his brother will be 19 years old.
Answer: A) 19
Explanation:
This problem involves understanding age relationships and applying basic arithmetic. Initially, we noted that Brian’s brother is 16, which is derived from the information that he is twice Brian’s age. The problem asks for the brother’s age when Brian reaches 11, which means we need to consider the time that will pass until that age is reached. Since 3 years will pass, we simply add those years to the brother’s current age of 16.
It’s crucial to recognize that the age difference between the two will always be the same; therefore, regardless of how old Brian gets, his brother will always be 8 years older than him. This relationship simplifies the calculation because we can easily add 3 years to 16 to find that Brian’s brother will be 19 when Brian is 11.