Logic Puzzle

I need to figure out how many sisters Sally has.

Given information:

• Sally is a girl
• Sally has 3 brothers

Now, each brother has 2 sisters.

If each of Sally's brothers has 2 sisters, and Sally is one of those sisters, then there must be one more sister besides Sally.

Let me verify:

• Total sisters in the family: Sally + 1 other sister = 2 sisters
• Each of the 3 brothers would have these same 2 sisters
• This checks out ✓

Therefore, Sally has 1 sister.