## Puzzle challenges!

**Moderator:** Forum Moderators

### Re: Puzzle challenges!

Time to bring the puzzle thread back to life, at least for a little while! Here's a puzzle that some of my friends were surprised I hadn't heard before, apparently it's a classic.

In front of you are two fuses, both a meter long, and a lighter. You know that if you lit one end of either fuse on fire, it would take exactly one hour for the entire thing to burn away. Your task is to use these two fuses to measure exactly 45 minutes.

It sounds easy at first, but then you realize that the rate at which the fire spreads isn't known; maybe it will travel uniformly from one end to the other over the course of the hour, or maybe it will burn through 90% of the fuse in 10 minutes and slowly smolder through the remaining centimeters for the next 50. In other words, seeing when the fire crosses one's halfway point doesn't tell you that 30 minutes have passed. On top of that, the two fuses aren't identical, so watching one burn doesn't tell you anything about the other's rate. All you know for sure is that it takes an hour for the fire to get from one end to the other.

Measuring 45 minutes with nothing but two silly fuses and a lighter will take some creativity, but there is a good answer.

In front of you are two fuses, both a meter long, and a lighter. You know that if you lit one end of either fuse on fire, it would take exactly one hour for the entire thing to burn away. Your task is to use these two fuses to measure exactly 45 minutes.

It sounds easy at first, but then you realize that the rate at which the fire spreads isn't known; maybe it will travel uniformly from one end to the other over the course of the hour, or maybe it will burn through 90% of the fuse in 10 minutes and slowly smolder through the remaining centimeters for the next 50. In other words, seeing when the fire crosses one's halfway point doesn't tell you that 30 minutes have passed. On top of that, the two fuses aren't identical, so watching one burn doesn't tell you anything about the other's rate. All you know for sure is that it takes an hour for the fire to get from one end to the other.

Measuring 45 minutes with nothing but two silly fuses and a lighter will take some creativity, but there is a good answer.

The last few months have been nothing but one big, painful reminder that TIMTLTW.

Creator of Armory Mod, The Rising Underworld, and Voyage of a Drake: an RPG

Creator of Armory Mod, The Rising Underworld, and Voyage of a Drake: an RPG

### Re: Puzzle challenges!

**Spoiler:**

### Re: Puzzle challenges!

Yep, that's exactly right!

If anyone is interested, I found a place with several more good riddles: the TED talks youtube channel. Here is a link to the playlist. A lot of them are repeats of what's already in this topic (in fact a couple of the ones I posted a stolen straight from it) and some of them have silly think-outside-the-box answers that don't feel satisfying at all, but there are a decent amount of good, new ones. For example, the Seven Planets riddle, about halfway through the playlist, is really good.

If anyone is interested, I found a place with several more good riddles: the TED talks youtube channel. Here is a link to the playlist. A lot of them are repeats of what's already in this topic (in fact a couple of the ones I posted a stolen straight from it) and some of them have silly think-outside-the-box answers that don't feel satisfying at all, but there are a decent amount of good, new ones. For example, the Seven Planets riddle, about halfway through the playlist, is really good.

The last few months have been nothing but one big, painful reminder that TIMTLTW.

Creator of Armory Mod, The Rising Underworld, and Voyage of a Drake: an RPG

Creator of Armory Mod, The Rising Underworld, and Voyage of a Drake: an RPG

### Re: Puzzle challenges!

Cool, it's great to see this thread again!

I've got a quick one:

You're getting dressed in the dark and want to put on a matching pair of socks. You know you have two piles, one with 1 black sock and 2 white socks, and another with 2 black socks and 2 white socks. (And of course, you can't tell the two colors apart in the dark.) You decide to choose a pile and then randomly choose 2 socks from that pile and wear them. Which pile should you choose to maximize your chance of getting a matching pair (or are they the same)?

See, this one has real world applications

I've got a quick one:

You're getting dressed in the dark and want to put on a matching pair of socks. You know you have two piles, one with 1 black sock and 2 white socks, and another with 2 black socks and 2 white socks. (And of course, you can't tell the two colors apart in the dark.) You decide to choose a pile and then randomly choose 2 socks from that pile and wear them. Which pile should you choose to maximize your chance of getting a matching pair (or are they the same)?

See, this one has real world applications

Screenshot playthroughs: Let's Play Dead Water, Let's Play Invasion from the Unknown and Let's Play After the Storm

### Re: Puzzle challenges!

That's mostly right, just a tiny mistake:

**Spoiler:**

Screenshot playthroughs: Let's Play Dead Water, Let's Play Invasion from the Unknown and Let's Play After the Storm

### Re: Puzzle challenges!

Ah yes, what a silly mistake. You are right.

### Re: Puzzle challenges!

I remembered another little probability problem so I'm using it as an excuse to revive this thread

A and B are playing a game: A flips 101 fair coins, and B flips 100 fair coins. The person who gets the most heads wins.

Who do you think is more likely to win?

A and B are playing a game: A flips 101 fair coins, and B flips 100 fair coins. The person who gets the most heads wins.

Who do you think is more likely to win?

Screenshot playthroughs: Let's Play Dead Water, Let's Play Invasion from the Unknown and Let's Play After the Storm

- WTrawi
**Posts:**136**Joined:**July 11th, 2016, 6:04 pm**Location:**My location is not public, but I know YOURS and I can use it against you.

### Re: Puzzle challenges!

I'm so glad this thread is back again

Not very active on the forum anymore, but I still read it, and I also still play Wesnoth and draw a bit.

### Re: Puzzle challenges!

B cause he has one unit smaller pool of probability to work with ?

### Re: Puzzle challenges!

I don't understand what you mean, but no it's not B - after all B has less coins total, and we're counting the total number of heads each person flips.

Here's a hint:

What about this game - A flips 101 fair coins, B flips 100 fair coins, and the person who gets the most

Here's a hint:

What about this game - A flips 101 fair coins, B flips 100 fair coins, and the person who gets the most

*tails*wins?### Re: Puzzle challenges!

Well it seems obvious that A would be more likely to win either game. I just think no one is brave enough to say it because these statistics questions always have some tricky, unintuitive answer.

But after all, it's the same as if A flipped 100 times and B only flipped 2; of course A is more likely to win. It isn't nearly as big of an advantage in the original question, but it's a small advantage for the same reason.

But after all, it's the same as if A flipped 100 times and B only flipped 2; of course A is more likely to win. It isn't nearly as big of an advantage in the original question, but it's a small advantage for the same reason.

The last few months have been nothing but one big, painful reminder that TIMTLTW.

Creator of Armory Mod, The Rising Underworld, and Voyage of a Drake: an RPG

Creator of Armory Mod, The Rising Underworld, and Voyage of a Drake: an RPG

### Re: Puzzle challenges!

EDIT: Ooooops I totally asked the wrong question...I completely forgot it's possible for neither person to win the game. That's what I get for posting from memory Of course your answer to the original question was right

What I should have asked was the probability A would win.

It turns out the probability A would win is 1/2 (kind of counterintuitive, since you'd think it'd be greater):

What I should have asked was the probability A would win.

It turns out the probability A would win is 1/2 (kind of counterintuitive, since you'd think it'd be greater):

**Spoiler:**