Let's break down the statement made by Sai step-by-step to understand the relationship between the girl and Sai.

Understanding the Blood Relation Statement

Sai's statement is: “She is the only daughter of the father, who is the only son of my father’s father.”

We need to identify the key individuals mentioned relative to Sai:

• Sai's father's father
• The only son of Sai's father's father
• The father, who is the only son of Sai's father's father
• The only daughter of this father

Step-by-Step Analysis of the Relationship

1. “my father’s father”: This refers to Sai's paternal grandfather.
2. “the only son of my father’s father”: A person's paternal grandfather has one or more sons. If the statement says "the only son", it means Sai's grandfather had only one son. That only son must be Sai's father.
3. “the father, who is the only son of my father’s father”: As determined in the previous step, this entire phrase refers to Sai's father.
4. “She is the only daughter of the father [Sai's father]”: This means the girl being pointed at is the only daughter of Sai's father.

So, the girl is the only daughter of Sai's father. Since Sai is the son of Sai's father, and the girl is the only daughter of Sai's father, they share the same parents.

Determining the Relationship to Sai

If the girl is the only daughter of Sai's father, and Sai is also a child of Sai's father, then the girl and Sai are siblings. Since she is the only daughter, she must be Sai's sister.

Let's visualize this with a simple family structure:

• Grandfather (Sai's father's father)
• Father (The only son of the Grandfather, which is Sai's father)
• Children of the Father (Sai and the Girl)

The girl is stated to be the only daughter of Sai's father. Therefore, the girl is Sai's sister.

Conclusion: How the Girl is Related to Sai

Based on the analysis of the statement, the girl is the only daughter of Sai's father. This makes her Sai's sister.

Revision Table: Blood Relations

Understanding common blood relations is key to solving these puzzles.

• Father's father: Paternal Grandfather
• Father's mother: Paternal Grandmother
• Mother's father: Maternal Grandfather
• Mother's mother: Maternal Grandmother
• Father's son: Brother (if you are also a child of the father)
• Father's daughter: Sister (if you are also a child of the father)
• Son of your father's father (only son): Your father
• Daughter of your father's father: Your father's sister (Aunt)

Additional Information: Solving Blood Relation Puzzles

Blood relation puzzles require careful reading and breaking down complex sentences into simpler parts. Here are some tips:

• Start from the end of the relation statement, often the part related to "my" or "your", and work backwards.
• Draw a family tree or diagram if the relations are complex. Use symbols for male, female, and relationships (e.g., a line for sibling, a double line for marriage, a vertical line for parent-child).
• Identify the 'central' person the relations are described from (in this case, Sai).
• Convert relations like "father's father" into single terms like "grandfather".
• Pay close attention to words like "only son" or "only daughter" as they are crucial constraints.