Logic Puzzle

Alright, let's tackle this problem step by step. The question is:

Sally (a girl) has 3 brothers. Each brother has 2 sisters. How many sisters does Sally have?

At first glance, it seems straightforward, but let's break it down to ensure we understand it correctly.

Understanding the Problem

1. Sally's Brothers: We're told that Sally has 3 brothers. So, in the family, there are Sally and her 3 brothers. That's 1 girl (Sally) + 3 boys = 4 children so far.

2. Each Brother's Sisters: Now, it's stated that each brother has 2 sisters. This is where we need to be careful. Who are these sisters?

   • One sister is definitely Sally, since she's a girl in the family.
   • The other sister must be someone else because the number is 2, not 1.

Identifying the Sisters

Let's list out the siblings based on the information:

• Sally: Girl
• Brother 1: Boy
• Brother 2: Boy
• Brother 3: Boy

Now, for each brother, they have 2 sisters. We know one sister is Sally. So, where does the other sister come from?

This implies there must be another girl in the family besides Sally. Let's call this other sister "Anna" for clarity.

So now, the siblings are:

• Sally: Girl
• Anna: Girl
• Brother 1: Boy
• Brother 2: Boy
• Brother 3: Boy

Now, let's verify:

• Sally's brothers: Brother 1, Brother 2, Brother 3 (3 brothers) — matches the given.
• Each brother's sisters:
  • Brother 1's sisters: Sally and Anna (2 sisters)
  • Brother 2's sisters: Sally and Anna (2 sisters)
  • Brother 3's sisters: Sally and Anna (2 sisters)

This checks out.

Counting Sally's Sisters

Now, the question asks: How many sisters does Sally have?

From our list:

• Sally's siblings: Anna, Brother 1, Brother 2, Brother 3.
• Sisters: Anna.

So, Sally has 1 sister (Anna).

Wait a minute, but earlier we thought there are two sisters (Sally and Anna). But the question is about how many sisters Sally has, not how many sisters there are in total.

Sally is a girl, and Anna is another girl. So, from Sally's perspective, her sister is Anna. She doesn't count herself when counting her sisters.

Verifying the Count

Let me rephrase to ensure clarity:

• Total girls in the family: Sally and Anna (2 girls).
• Total boys in the family: 3 brothers.

For any brother:

• Sisters are Sally and Anna (2 sisters) — matches the given.

For Sally:

• Sisters: Only Anna (since Sally doesn't count herself).

Therefore, Sally has 1 sister.

Potential Missteps

Initially, one might think that since each brother has 2 sisters, and one is Sally, the other must be another sister, leading to the conclusion that there are 2 sisters in total (Sally and one more). Then, when asked how many sisters Sally has, one might mistakenly say 2, counting both Sally and the other sister. But that would be incorrect because Sally cannot be her own sister.

The correct interpretation is that the "2 sisters" each brother has are Sally and one other sister (let's say Anna). Therefore, Sally's sisters are just Anna, making it 1 sister.

Final Answer

After carefully analyzing the information:

Sally has 1 sister.