Puzzles - Week 1

As pointed out by iforget, these puzzles are clogging up the forum and answers come out way too quickly for some to catch up. So here's week one of the puzzle thread! I'll post one a week to get things going and see how things go from there.

There are 3 hints for each puzzle, so use teamwork to decide when one is needed.


Puzzle 1 - Brother and Sister

A boy and his big sister are sitting around the kitchen table chatting.

"You know, Sis, if I took away two years from my age and gave them to you, you'd be twice my age, huh!"

"Well, why don't you just give me one more on top of that? Then I'll be three times your age."

So just how old is each sibling?

When you read this, don't scroll down until you think you've got the answer, then post. That way it wont be spoiled for you!

12 Replies

How the final transfer of one year can cause the sister's age to treble her brothers is beyond me. All I have is Brother age 5 - 2 = age 3

Sister age 4 + 2 = age 6

So, yes the sister is now double her brother's age but she's actually 4 which makes her his 'little' sister not his 'big' one as you suggested.

The whole thing has completely done my head in & I'm going to bed. :o

My subject was English. . . . . . . . NEVER maths !! xx


Six is screaming out at me but I don't know who or why so I can't work the rest out... How annoying! And who and why 6? Is some one nine then? Or did I go completely wrong way?

Sorry, can't do better I'm afraid.


I think they are twins

Both are 6 to start with he gives her 2

He becomes 4 and she becomes 8

If he gives her 3 he becomes 3

And she becomes 9

But that doesn't explain the big sister bit, unless she is taller than him or born a few minutes before him! :)


Well done Hedgehog ; I think that's what's called 'Lateral Thinking' !! ;-) x


I don't know about lateral thinking. I think it's more to do with a suspicious personality - where's the catch! :)



Both siblings being 6 is correct!

The conditions in the puzzle only work out if both the brother and sister are currently six.

The two siblings mus have been born within a year of each other.


Yay go me :)

First time I ever got an algebra type question right!

1 like

Which means I got it correct but still have no idea how?! You got to love BI


I'm fairly good at algebra, or at least I used to be, before my injury. Word problems, not so much. Anyway, maybe I'm reading the problem wrong. I tried 6. Yes if their both 6 then take away 2 from the one, and add to the other does, it does make 8 or 4*2. So far both siblings being 6 works fine. Perhaps I'm reading the problem wrong, but I read the entire question, including the sisters comment where she states, "well, why don't you just give me one more on top of that? Then I'll be three times your age." I think this makes the problem unsolvable, because adding three (or the original two + the additional one) to 6 makes 9, meaning that the brother is only 1/3 that age or only 3.


Ok so both kids are 6 years old

Take two from sister to brother (sis becomes 8, bro becomes 4, i.e now twice his age)

Now take another one from the sister and add it to the brother (sis becomes 9, bro becomes 3, i.e now three times his age)


BSA, do you get these puzzles from Professor Layton games? I like those games :).

I have solved that question before but it was quite a while ago when I did it.


Heck if I know, I have them all written down in my book


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