It's Not Nice To Tease One's Brain

I'm can't imagine the level of anticipation that has been building over the brain teasers from my previous post...so, without further ado, I present to you the answers...

1. I have two coins that add up to $30 cents, and one of them is not a nickel. What are the two coins that I have? [ANSWER: A quarter and a nickel. You'll notice I said that "one of them is not a nickel", and one of them is indeed not a nickel, it's a quarter.]
   
2. A magician claims the following: using his hands, he can throw a ball, have it come to a complete stop, and then reverse its direction, all without the ball ever touching any surface or being manipulated by any wires or other objects. How is this possible? [ANSWER: The magician threw the ball straight up into the air (congrats to the anonymous comment that knew this one).]
   
3. You are traveling with a wolf, a cow, and a barrel of hay, when you come to a river that you must cross. Using a small row boat, you can only travel across the river with ONE of the three items at a time. However, the wolf can never be left alone with the cow (because he'd eat the cow) and the cow can never be left alone with the hay (because he'd eat the hay). Using the small row boat to take trips back and forth across the river, how could you get all three items across the river safely? [ANSWER: First, you take the cow over the river, leave him on the other side by himself, and row back alone. Then, you take the hay over the river (leaving the wolf by himself), drop off the hay, and take the cow back to the original side of the river (leaving the hay alone on the other side). Next, you take the wolf over the river (leaving the cow alone on the original side), leave the wolf with the hay, and go back alone to the original side. Last, you take the cow back over the river, and all three items are across the river with you. (congrats again to the anonymous comment that knew this one).]
4. You have two empty containers, one of which measures exactly 3 gallons and one of which measures exactly 5 gallons. Using the two containers and a nearby water source, how would you go about measuring EXACTLY 4 gallons of water (let's all thank 'Die Hard with a Vengeance' for this one)? [ANSWER: There is actually two ways to do this, and here they are...(Way #1) First, you fill the five gallon jug, use the five gallon jug to fill the 3 gallon jug (thus having 2 gallons in the five gallon jug). Next, you empty the 3 gallon jug, and pour the 2 gallons from the 5 gallon jug into the 3 gallon jug (thus having 1 empty gallon of space in the 3 gallon jug), Last, you fill up the 5 gallon jug again, use the 5 gallon jug to fill up the 1 gallon of empty space in the 3 gallon jug, and then you will be left with exactly 4 gallons in the 5 gallon jug...OR...(Way #2) Fill up the 3 gallon jug and empty it into the 5 gallon jug. Next, fill up the 3 gallon jug again and use it to fill up the 5 gallon jug with 2 more gallons (you will be left with exactly 1 gallon in the 3 gallon jug). Next, empty out the entire 5 gallon jug, and pour the 1 gallon from the 3 gallon jug into the 5 gallon jug. Last, fill up the entire 3 gallon jug, pour it into the 5 gallon jug, and you will have exactly 4 gallons in the 5 gallon jug...WOW, that's long (congrats once again to the anonymous comment that knew this one).]
5. You're traveling through the woods and you come to a fork in the path. Although you do not know which path is the correct path to continue on, you do know that one path of the fork will lead you to safety, while the other path of the fork will lead to certain death. There are two forest dwellers standing at the fork that do indeed know the correct path to take, however, one of them will always tell the truth and one of them will always lie (and you do not know which forest dweller is the truthful one and which is the liar). What question could you ask either of the two forest dwellers to find out, with 100% certainty, which path is the correct path to safety? [ANSWER: This is a tough one. The question that you could ask either forest dweller to find the correct path with 100% certainty would be the following: "If I were to ask the other forest dweller which path was the path leading to certain death, what would he say?". Now think about this one for a second because it's tough to wrap your head around...I'll explain. There are two forest dwellers, one truthful and one a liar, so you have to think of how each of them would answer this question. First, if you end up asking the truthful forest dweller this question, he would be telling you about what the LIAR would say is the dangerous path; and since the liar lies, the liar would actually point to the path of safety as the path that would lead to certain death; therefore, in answering the question about the liar's lie, the truthful one would be showing us the path of safety. Second, if you end up asking the liar forest dweller the question, he would be telling you about what the TRUTHFUL forest dweller would say is the dangerous path; and since the truthful guy tells the truth, he would point to the actual dangerous path; BUT, we're asking the liar the question, so in answering the question he would actually reverse the truth of the truthful one and, hence, tell us the path to safety. So, asking either one the question would result in them pointing to the path of safety, guaranteed.]

...wow, I think my head just exploded.