Ravi's brother is 3 years older than Ravi. Ravi's father was 28 years old when Ravi's sister was born, and his mother was 26 years old when Ravi was born. If Ravi's sister was 4 years old when his brother was born, what were the ages of Ravi's father and mother respectively when the brother was born?

Introduction / Context:
This is a family age puzzle involving Ravi, his brother, his sister, and their parents. You are given information about the parents' ages at specific birth events and the age differences between the siblings. The question asks for the ages of the father and mother when Ravi's brother was born. This type of question tests your ability to manage time-line reasoning and age differences consistently.

Given Data / Assumptions:

• Ravi's brother is 3 years older than Ravi.
• Ravi's father was 28 years old when the sister was born.
• Ravi's mother was 26 years old when Ravi was born.
• The sister was 4 years old when the brother was born.
• We assume ages are counted in whole years and ignore months.

Concept / Approach:
We can use age differences rather than absolute ages. The crucial piece is that the father is always 28 years older than the sister and the mother is always 26 years older than Ravi. We are told that the sister was 4 years old when the brother was born, so we can calculate the parents' ages at that time using their fixed differences with the sister and with Ravi, being careful with relative timing. A useful trick is to think of negative ages for children not yet born when going further back in time, simply to preserve the constant age differences.

Step-by-Step Solution:
Step 1: Since the father was 28 when the sister was born, the father is always 28 years older than the sister.Step 2: The mother was 26 when Ravi was born, so the mother is always 26 years older than Ravi.Step 3: At the time when the brother was born, the sister was 4 years old.Step 4: Therefore, at the brother's birth, father's age = sister's age + 28 = 4 + 28 = 32 years.Step 5: The brother is 3 years older than Ravi, so at the brother's birth, Ravi was not yet born and would be born 3 years later. This means at that moment, Ravi's age would be -3 if we extend the difference backwards.Step 6: Since the mother is always 26 years older than Ravi, at the brother's birth, mother's age = Ravi's age + 26 = -3 + 26 = 23 years.Step 7: Hence, when the brother was born, father was 32 years old and mother was 23 years old.

Verification / Alternative check:
We can move forward along the time line to double check. At the brother's birth, father is 32 and mother is 23. Four years later, when the sister is born, father would be 36 and mother would be 27, yet the problem states father was 28 at sister's birth, so this forward check appears inconsistent if we mistakenly treat the sister's age relation incorrectly. The key is that the sister being 4 years old at the time of the brother's birth means the sister was born 4 years before the brother, so earlier in the time line. If at the sister's birth father was 28, then 4 years later, at the brother's birth, father is 32, which fits perfectly. Similarly, Ravi is born 3 years after the brother, so at Ravi's birth father is 35 and mother is 26, matching the given mother's age at Ravi's birth and confirming the calculation.

Why Other Options Are Wrong:
Option B (32 years, 29 years): This implies the mother is only 3 years younger than the father, which does not match the ages at Ravi's birth.
Option C (35 years, 29 years) and Option D (35 years, 33 years): These combinations do not maintain the correct age gaps with the sister and Ravi when checked against the original statements.

Common Pitfalls:
Many students misinterpret the direction of time when they read that the sister was 4 years old when the brother was born. It is easy to confuse which child is older. Another frequent mistake is to ignore that parent-child age differences remain constant through time. Drawing a simple time-line with labelled events for each birth helps to avoid such confusion and leads to accurate age calculations.

Final Answer:
Ravi's father and mother were respectively 32 years and 23 years old when the brother was born.