MrRubix's Riddle Thread

[MrRubix_MK5]

explain.

[Reach]

Originally Posted by MrRubix_MK5

explain.

I'll explain if it's right.

If not I'll work on my by hand math skills...alternatively I'll use the pc calculator but oh boy that thing sucks. Alternatively I'll realize my logic is not optimal.

I think it's wrong, but I'm not recalculating it right now XD

[Tasselfoot]

you know what the REAL solution to all this is.... i'm faster than emerald and fractal. end of story.

[MrRubix_MK5]

Reach: 7.3 is wrong. While you're right that one person gets there in 7.3 using what I think your strategy is, I think you'll find the other takes 8.

[foilman8805]

Put emerald on the handle bars, Fractal on the pegs and have Tass ride his balls off.

Two hours.

Kidding, I see that can't happen anyways.

[Reach]

Originally Posted by MrRubix_MK5

Reach: 7.3 is wrong. While you're right that one person gets there in 7.3 using what I think your strategy is, I think you'll find the other takes 8.

Yeah it is wrong. I decided I might as well check the calculations again.

I think I can fix it though. Probably not tonight.

[Netjet!]

How about emerald rides the bike, and tass carries fractal. Fractal and emerald would then switch after 10 miles. after 20, they'd switch again, until they reach the point of 30. And tass would carry each of them, and you didn't say he slows down if he carries them.

So:

(Emerald - 5mph for 10 miles) and (Tass carries Fractal, goes 5mph for 10 miles) = 2 hours.

Emerald and Fractal Switch.

(Fractal - 5mph for 10 miles) and (Tass carries Emerald, goes 5mph for 10 miles) = 2 hours.

Fractal and Emerald Switch.

(Emerald - 5mph for 10 miles) and (Tass carries Fractal, goes 5mph for 10 miles) = 2 hours.

So the final solution would be 6 hours. I'm not sure if this is the correct way though. But it looks like the optimal choice.

[MahouMinachan]

He did say, "the bike can only carry one person at a time," which probably means it'll break if more than one person is on at the same time.

If only this was easy like the "multiple people doing one job" problems in algebra.

[Netjet!]

Tass would be walking, and he'd be carrying fractal/emerald at different intervals. Only one person ride the bike.

[MahouMinachan]

If you think that way, then might as well say everyone on Tass and it'll be the same thing...

[Reach]

Originally Posted by MrRubix_MK5

Reach: 7.3 is wrong. While you're right that one person gets there in 7.3 using what I think your strategy is, I think you'll find the other takes 8.

Ok, if I correct the error I seem to get 7.6 hours. I guess this is wrong, given other people have said it.

If there's a more complicated way of dealing with this for an optimal path I'll be interested in seeing the answer.


Personally, I assume everyone finishes at the same time. There's no benefit of having someone arrive at the finish before the others, since Tass can wheel the bike back to someone. Parsimoniously speaking, Tass should only backtrack on the bike once. Also, parsimoniously speaking, Tass should backtrack on the bike at the exact point when it will take the person he took the bike from the same time to reach the finish that it will take Tass to backtrack, give up the bike and then reach the finish with the other person.

If you work this out the answer is 7.6

[cry4eternity]

@Netjet:

He didn't say they COULD be carried either...

And even if they could, why would they need to switch? Tass walks at the same rate that either of the others rides. He could carry the whole way.

@thread:
I don't think it's possible to get below 7.6 hours... What am I missing?

[Netjet!]

Oh yeah they wouldn't need to switch :/

[MahouMinachan]

Okay, I really think the optimal is 7.6 hours.

[windsurfer-sp]

First Idea:
The aim is to get the last person to arrive as quickly as possible. People

Im guessing the idea is that one rides the bike and then drops it, leaving the other to pick up and ride it. As far as im concerned Tass should walk the full distance, as when ever he rides the bike the others have to walk, which means they will arrive later.

So Tass gets there in 30/5, or 6 hours.

The other two I guess, as there stats are even should ride equal distances. So I say that they both take 15/5 + 15/3 hours each. Crap 8 hours.

Will post second hopefully better idea later.

[MahouMinachan]

Here's my math Rubix.

Pretty much I did this a different way:
I decided how long would it take for the Emerald and Tass to go together to leave Fractal behind 18 miles. That would take 9 hours (27 miles fractal, 45 miles emerald/tass). That would give Tass 1 hour to go back to get fractalon the bike. Fractal would go another 3 miles per hour, and emerald would start walking 3 mph.

After 10 total hours, Tass and fractal would meet up at 30 miles, while emerald would be way up at 48 miles. After 9 more hours (and fractal on bike while tass walks besides him), Tass and fractal would finally catch up to emerald at 75 miles. A total of 19 hours.

Using the 75 miles, I'll compare it to 30 miles.

So 30/75=.4, or 40% of the way.

Therefore, 19*.4=7.6.

The answer I have is 7.6 hours, or 7 hours 36 minutes.

Edit: I'm pretty sure Rubix wanted this in our answer since it's part of the riddle's questions.

[MrRubix_MK5]

People may have given the right answer, but I want them to be confident in their answer. Otherwise it's too easy.

But, yes, 7.6 is the right answer. Can't go faster than that. I was waiting until someone actually proved it with their math instead of just guessing.

[Reach]

Six dots are marked on a flat surface so that no more than two at a time may be connected by any straight line of whatever length. If a straight line is drawn through each and every pair of dots and extends beyond them any desired distance, what is the maximum number of different points at which these lines may intersect one another?

[cry4eternity]

of course... grr I think I was the first to post 7.6 too

I figured it out by calculating:
If Emerald starts out on a bike, then gets off at some point x miles in, Tass can travel 1/3 that distance back, and meet Fractal at that exact point. So I drew these curves and figured out that having Emerald switch 18 miles in was the fastest it could get...


My curves kinda looked like this:

          18
 -------------------          Emerald
              6    /
           --------           Tass
           \    18
            ------------------Fractal

[MrRubix_MK5]

New riddle. This one's tricky. Good luck!