HCF question

[kateJ]

My Dad is 54 and my Mum is 36. I can divide both their ages exactly by both my age and my big brother's age. What is the oldest that my brother could be? How old could I be? How old do you think I am?


Answer: Brother = 18 Me: 6
The brother is 18 (HCF of both numbers). But why is the next answer 6 and not 9?

Many thanks

[mystery]

Was it multiple choice?

[parent2013]

I'll go with the answer 6 and 9 ( 3 years age gap between brothers seems more reasonable than 12 )

Which book is it from?

[kateJ]

Thanks parent2013

It's taken from: 'So you really want to learn Maths Book 1' Galore Park. The answer book states that part 2 of the question is 6 or 2 - no mention of 9 at all!

[parent2013]

Actually on the second thought (after reading the question carefully), it says

"What is the oldest that my brother could be" - which is as you said HCF i.e. 18

Both 6 and 9 seems ok to me.

Gotta go

[ToadMum]

My Dad is 54 and my Mum is 36. I can divide both their ages exactly by both my age and my big brother's age. What is the oldest that my brother could be? How old could I be? How old do you think I am?


Answer: Brother = 18 Me: 6
The brother is 18 (HCF of both numbers). But why is the next answer 6 and not 9?

Many thanks

The answer to 'How old do you think I am?' would surely be 9 rather than 6, if that - how many 6 year olds do you know who are that conversant with their 6 / 9 / 18 times tables ? Unless there is something glaringly obvious that we are all missing, it appears to be a very poorly-written question...

[mystery]

You said what I was going to say. Galore Park - crazy question and crazy answer. Is the rest of the book like that?

Or maybe there is some significant reason why Mum and Dad would not have produced a baby when they were 45 and 27 respectively or why a 9 year gap should be avoided at all costs?

She had that first child when she was pretty young and her husband was twice her age. Curiouser and curiouser. Do you think he was her teacher?

Do we know who they are? Far more interesting than guessing whether or not it's a genius toddler that wrote the question.

[Proud_Dad]

Both brother and the questioner could be 18.

The question refers to "big" rather than "older" brother so they could be 2 twins of different weights/heights.

[mystery]