Logic Puzzle

Let me work through this step by step.

Given information:

• Sally has 3 brothers
• Each brother has 2 sisters

Let me think about who the sisters are:

• Sally is one sister
• Since each of the 3 brothers has 2 sisters, and Sally is one of them, there must be 1 other sister

So the two sisters are:

1. Sally
2. One other sister (who is also a sister to all 3 brothers)

Therefore, Sally has 1 sister.

Sally has 1 sister.