## Math mystery (3)

Anything goes, but keep it seemly...

### Math mystery (3)

2 mathematicians meet each other in the street and start a conversation.

"How many children do you have?"

"3"

"How old are they?"

"You'll have to guess. The product of their ages is 36"

"Hmm.. too many options. What else can you tell me?"

"OK. The sum of their ages is equal to the number of the house at the other side of the street."

"I'm close, but still missing a clue"

"Right. The eldest kid plays piano"

"That's it! Thanks!"

Do you know the age of the mathematician's kids?

Ruud.
Ruud

Posts: 664
Joined: 28 October 2005

### Re: Math mystery (3)

Ruud wrote:Do you know the age of the mathematician's kids?

It seems too easy so I suspect I'm wrong - I'll say 3, 6 and 2years.
I'm still wading through all the replies in MM(2) which has given me a lot to think about - enjoying all these posts but wish I was quicker on the uptake. I'd be able to 'compete' better if a joke was allowed to wind up each thread or would it spoil things?

Cec
Cec

Posts: 1039
Joined: 16 June 2005

The kids are 2,2,9 respectively...

There're only 8 combinations of the ages triples:

Code: Select all
`Ages   Sum1,1,36  381,2,18  211,3,12  161,4,9   141,6,6   132,2,9   132,3,6   113,3,4   10`

Now only (1,6,6) & (2,2,9) totalling to the same sum, 13, which must be the street number of that house across the street...

There is an eldest kid, so apprently they cannot be a pair of 6-year-old twins... (But in fact almost every twins have an elder one... anyway that's how the story's supposed to go...)
udosuk

Posts: 2698
Joined: 17 July 2005

Why does the number of the house have to be 13?
emm

Posts: 987
Joined: 02 July 2005

### dis-ambiguation

emm wrote:Why does the number of the house have to be 13?

because the number of the house
was not sufficient to answer the question -
an extra clue was still needed for dis-ambiguation:
"The sum of their ages is equal to the number of the house at the other side of the street."

"I'm close, but still missing a clue"

Pat

Posts: 3595
Joined: 18 July 2005

### Maths Mystery (3)

emm wrote:Why does the number of the house have to be 13?

I note Pat has answered this but I still have the same query as emm.

The three clues don't say the house across the street has to be No. 13 - it could be any number say No. 14 in which case the ages of the three kids could also be the 1,4,and 9 years combination. Taking this further, as the house number is not disclosed the kid's ages could therefor be any one of the eight age combinations listed by udosuk. Am I missing something which restricts the answer solely to 2,2 and 9 years?

Cec
Cec

Posts: 1039
Joined: 16 June 2005

Hi Cec,

if you look at the list of all possible combinations, you will notice that all combinations sum up to a different total, except the combinations 1,6,6 and 2,2,9, which both sum up to 13.

If the house number would not have been 13, the second mathematician would have known the answer and not need another clue.

Ruud.
Ruud

Posts: 664
Joined: 28 October 2005

### Mystery maths (3)

Yes Ruud I get it now. A very clever riddle.

Cec
Cec

Posts: 1039
Joined: 16 June 2005

I believe there is an assumption being made here, and that is that both mathematicians can see the number of the house across the road.

If they cannot see the number then there is no answer.

So both mathematicians can see the number, any number other than 13 and the riddle can be solved, only if the number is 13 does it require an additional clue.

MCC

I see cec has finally got it. I will leave my post anyway.
MCC

Posts: 1275
Joined: 08 June 2005