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032 - Broken Lance033 - Brothers 'n' Sisters034 - The Mysterious Memo

Brothers 'n' Sisters is a puzzle in Professor Layton and the Unwound Future.

Puzzle

US Version

Below are three siblings: A, B, and C.

A: "I have one older brother and three younger sisters."

B: "I have two older brothers and two younger sisters."

C: "I have three older brothers and one younger sister."

For all of their statements to be true, what's the smallest possible number of siblings there can be in the family?

UK Version

There are three siblings: A, B and C.

A: "I have one older brother and three younger sisters."

B: "I have two older brothers and two younger sisters."

C: "I have three older brothers and one younger sister."

Given that all their statements are true, what is the lowest possible number of siblings in this family?

Hints

Click a Tab to reveal the Hint.

US Version

Think about A, B and C. Who's the oldest? Who's the youngest?

UK Version

Think about A, B and C.

Who's the oldest? Who's the youngest?

You know that A is the oldest, followed by B and then C.

A also has an older brother.

C also has a younger sister.

US Version

Try making a chart laying out the conditions of Hint Two, and mark the genders of each known sibling. You should make an important realization.

Also, just so you're clear, A is a male and B is a female.

UK Version

Try making a diagram based on the conditions mentioned in Hint 2, and note the genders of each known sibling. You should realise something important.

Also, just so you're clear, A is male and B is female.

There are more than five siblings.

If A has three younger sisters and C has three older brothers, than there must be at least three female siblings and three male siblings.


Solution

Incorrect

Too bad!

US Version

It's not as simple as it might seem at first glance.

UK Version

Remember that you want to find the minimum number of siblings.

Correct

US Version

Right on!

The smallest possible number of siblings is six.

At first glance, it might seem like there are only five. But the fact that A says he has three younger sisters means there must be at least three female siblings. Likewise, the fact that C says she has three older brothers means there must be at least three male siblings. So five siblings isn't quite enough.

UK Version

Bang on!

The lowest possible number of siblings is six.

At first glance, it might seem like there are only five. But the fact that A says he has three younger sisters means there must be at least three female siblings. Likewise, the fact that C says that she has three older brothers means there must also be at least three male siblings, so five siblings isn't quite enough.

UF033S
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