# Which road should he take?

TheBloop
Posers and Puzzles 29 Oct '05 03:12
1. 29 Oct '05 03:12
A man developed laryngitis and needed to see a specialist who's office was in a far away city. The problem is that on the way out of his town, the road forks. Neither of the resulting roads are marked. One road leads to the specialist's city while the other road leads you in the opposite direction.

To make matters worse, there are only two people who know which road leads to the specialist and which one leads in the opposite direction. These two people live at the spot where the road forks, and they are identical twins. One twin ALWAYS tells the truth, the other ALWAYS lies.

Since the man's laryngitis is worsening, he wants to ask ONE twin only ONE question in order to determine which road he needs to take.

What is the one question can he ask either twin which will enable him to immediately deduce which road is the correct road to the specialist?
2. 29 Oct '05 04:35
Originally posted by TheBloop
A man developed laryngitis and needed to see a specialist who's office was in a far away city. The problem is that on the way out of his town, the road forks. Neither of the resulting roads are marked. One road leads to the specialist's city while the other road leads you in the opposite direction.

To make matters worse, there are only two people who k ...[text shortened]... in which will enable him to immediately deduce which road is the correct road to the specialist?
Which way would your brother say goes to the specialist?

Then go the opposite way.
3. 29 Oct '05 21:00
Originally posted by perihelion
Which way would your brother say goes to the specialist?

Then go the opposite way.
You are correct.

The dishonest twin, knowing his brother always tells the truth, would lie, naming the wrong road.

The honest twin, knowing his brother always lies, would truthfully tell his brother's lie...again, naming the wrong road.

In either case, the man would know he had been misdirected, and would take the other road from the one that either twin told him... the right road.
4. 08 Nov '05 17:20
I think the obvious question to be asked here is... How the hell does he know that one always lies and one always tells the truth!?

Ollie.
5. XanthosNZ
Cancerous Bus Crash
08 Nov '05 17:50
I think the obvious question is how exactly does this puzzle differ from the various ones in the thread 4 down from this one?
6. 08 Nov '05 22:35
Originally posted by XanthosNZ
I think the obvious question is how exactly does this puzzle differ from the various ones in the thread 4 down from this one?
They are harder?
7. orfeo
Paralysed analyst
09 Nov '05 02:31
Originally posted by iamatiger
They are harder?
Nope.

The USEFUL facts are identical. Two options. Two people, one lies and one tells the truth. One question to ask.
8. 11 Nov '05 17:19
Originally posted by orfeo
Nope.

The USEFUL facts are identical. Two options. Two people, one lies and one tells the truth. One question to ask.
Assuming that you mean the questions in the thread
"You probably heard this one but i dont know the... "
Then the ones at the end of the thread are much harder than that!
9. orfeo
Paralysed analyst
11 Nov '05 23:11
Originally posted by iamatiger
Assuming that you mean the questions in the thread
"You probably heard this one but i dont know the... "
Then the ones at the end of the thread are much harder than that!
Yes, what I'm saying that this puzzle is exactly the same as the first one in that thread. If we wanted to, we could make harder variations of this one as well, but there's not really much point.
10. 12 Nov '05 16:11
Originally posted by XanthosNZ
I think the obvious question is how exactly does this puzzle differ from the various ones in the thread 4 down from this one?
I started this thread on Oct 28...the other thread started Nov 6
11. 14 Nov '05 15:36
Originally posted by TheBloop
I started this thread on Oct 28...the other thread started Nov 6
Yes, it was quite an easy one that, Xanthos, with lots of answers.
12. 30 Oct '06 16:18
This is a copy of one that has been done a hundred times on this site.