Sally has 3 brothers and each brother has 2 sisters. How many sisters does Sally have?This is a bit of a trick question! Sally has one sister. Here's why:
Sally and her brothers share the same sisters.
Since Sally is a girl, she is one of the two sisters that each of her brothers has.
Therefore, there is only one other sister besides Sally.There are two ways to think about this question:
Including Sally: If we consider Sally herself as one of her own sisters, then she would have 1 sister (herself) + 0 sisters (additional sisters besides herself) = 1 sister.
Excluding Sally: If we only consider sisters other than Sally herself, then each of her brothers has 2 sisters, but they all share the same two sisters. So, there are 0 sisters (additional sisters besides herself) = 0 sisters.
ChatGPT 4 (YMMV, I think I may have a custom prompt set):
Sally has 2 sisters. Each brother having 2 sisters just confirms Sally plus one more sister. ---
Wasn't expecting Gemini Advanced to clinch this one.
Sally's brothers all share the same sisters. They aren't each talking about a different set of sisters. Sally is one of those sisters! Each of her brothers has Sally as a sister. Since there are 2 sisters total (Sally and one other), Sally has one sister. Let me know if you'd like to try another brain teaser!