I think the riddle assumes that you'll ask a question about the roads, and the guards will simply point to the one that answers your question.

The crux of the riddle is that you must find a way to discern which road is which by asking one question to one of the guards, even though you don't know if he'll lie or tell the truth.

You ask them "which way will the other man tell me to go to get to the riches?" both of them will point to the same direction, take the other route.
This works because one lies and the other tells the truth, if you pit them against each other then they will reveal the incorrect path to take. Say for example the way we would like to go is the right hand road (the one that leads to riches). When we ask them "what way will the other guard tell me to go?" they will both answer left, as the truth teller will say (truthfully) that the other guard will say to go left, and the liar, knowing the truth teller will say you should go down the right hand side, will say left because it is a lie. So they both give you incorrect information and you go down the other path.

Close enough. Only, with the above explanation, they will be pointing to the road to damnation. This is the answer: "Which way would your brother say is the wrong way?" Let me explain. Lets call the road to riches "A" and the road to damnation "B". Lets start with the brother that always lies. If you ask him the said question, he will know that his brother will point to road B. He cannot point to road B, because he would be telling the truth. He will then lie and point to road A.

Now lets look at the brother who always tells the truth. If you ask him the said question, he knows his brother will not point road B, because his lying brother would never tell the truth. He knows his brother will lie and point to road A. Therefore, by telling the truth he will point to road A.


You ask the question out of the perspective of the brother.


Next riddle!

You are on a rowboat in the middle of a large, perfectly circular lake. On the perimeter of the lake is a monster who wants to eat you, but fortunately, he can't swim. He can run (along the perimeter) exactly 4x as fast as you can row, and he will always run towards the closest bit of shore to your boat. If two paths take him to this location equally quickly, he will arbitrarily choose one. If you can touch shore even for a second without the monster already being upon you, you can escape. The monster can reverse direction instantaneously and you can turn your boat instantaneously.

Suggest a strategy that will allow you to escape, and prove that it works.

Allow the rowboat to touch the shore (while standing in the back of the boat), let the monster get on the boat, and immediately jump in the water, and push the boat away from the shore (from underneath it. Swim to shore, the moister will be in the middle of the lake, and you will be free to go...

Reasonable, I grant you, but it wasn't the answer I was looking for. I'll add the condition that you yourself can't swim.

Alright then.

just a few questions:
-can the monster become fatigued or dizzy?
-can you become fatigued or dizzy?

Nope.

The story with the lake and the monster are just to give the puzzle a form of context, and is not something to be exploited. All that matters is that you are free to move within a circular area, and something else that can move four times as fast as you may only traverse the perimeter. And all you have to do is touch the edge without the other thing being there while you do it.

travel around in a circle in the lake that is 1/4 the size of the actual lake, when the monster is on the shore opposite you, you travel the 3/4 * radius distance required to get to the shore, he cannot travel fast enough to beat you there.

Correct: spiral outwards, keeping to the other side of the lake than the monster. Closer to the center, you can make a revolution of the lake faster than the monster, because it's a shorter distance. The furthest away from the centre you can get with this method is 1/4 of the way out, as here you'll both be making revolutions at the same speed. Once you get 1/4 of the way out, take a straight line to the shore. You only have to travel 3/4 = 0.75 units while the monster has to travel π = 3.14 units. 3.14 is more than 4 times 0.75, so you'll get to the edge before the monster does.

Next.

heres one. its kind of a riddle and kind of a joke. it goes something like only 10% of harvard students could get this right, and 90% of kindergarteners got it right.

what is more powerful than god, but more evil than the devil?

people are gonna hate the answer

-Max

I think there was a similar puzzle on the previous page, to which the answer is "I don't know". Kindergärtners are happy to accept defeat with a seemingly impossible puzzle, but Harvard graduates will assume that there's a solution, even if there isn't one.

Actually the whole thing is:
what is more powerful than god, more evil than the devil, rich people need it, poor people have it and if you eat it you will die.
To which the answer is 'nothing'.