2 numbers 2 integer numbers, each of them is larger than 1 and less than 50. F. knows their sum. G. knows their product. This is the dialog between them:
Peter
what kind of a q'n is this?
victim
Dave Neary
Answering the victim's question: this is one of the best puzzles I know :) Just from this dialog - almost no information at all - it's possible to say what the numbers are. Isn't it amazing?
Peter
so easy .. take me 45 min to solve it.. the answer is 3 and 4. just solve use regular way of math~!
Ping Li
the answers is 3 and 4. why?
Ping Li
I think 3 & 4 is wrong. Here is why. Let's assume that the numbers were 3 & 4:
David Clayworth
THE Whole idea
Ping Li
add: if G really knows the number before F, then F dont really need to have the last statement out for G to listen to which is F.: "And I know too"
Ping Li
Ping Li, I'm assuming that both people are telling the truth, and not competing with each other. If they are not telling the truth then there is no point to the question, because the numbers might be 2 & 3 and F and G are just lying about whether they know the answer or not.
David Clayworth
2, 3 is impossible coz sum of 5.. u can know the number right away. the 2 integer is bigger than " 1 ", which at least 2. Also in the question, it didnt tell you if they are telling truth or not. So if u make the assumption yourself, then it wont be logical.. and also, by the information that limited in the formula that i am given above. u will be take out lot of the sets. and the only set that fit in this dialog will left with 3,4..
Ping Li
oh btw, any other sets cant fit in this logic. coz will have too many variability
Ping Li
I think I have an answer for this.
David Clayworth
For the set of (4,13) will be right unless you make 2 assumptions a head: 1. The both guys are telling the 100%truth in the dialog. 2. the conversation take hell long time to talk, because some step they need to do some maths, or F is a genius that he can do all the maths in head for 2 sec~ between they are talking.
Ping Li
The answer is 1 and 4. Do the logic; it works. My whole office spent a day a couple years ago working this out; lost productivity but necessary in order to maintain our sanity. I actually posted this same question on this site back then. Apparently it rolled off. Thanks for putting it back up, Peter.
David Haner
Thats wrong since question said numbers are greater than 1.
Phani
I've worked it out comprehensively by computer. The answer is indeed 4 and 13.
Ham Fisted
Fog Creek Home |