Ok, so a friend of mine sent me this really odd riddle that, as far as I can tell, can't be solved. And since we have some serious brain-power on the forum, I thought I'd ask for your help... Here goes:

A 100 l barrel that is filled with 90 l of beer, plus three 15 l containers that are empty. You should obtain 50 l of beer. You can drink the beer once you have it. - That's all the info I got.

First instinct - plunge 15 l container into barrel to let 5 l spill out, then fill up all three = 50 l
This is not valid, no beer can be spillt.

Second idea - fill one 15 l container, then divide contents equally to give 3 times 5, pour two of them together (=10) and then fill up other two containers. Which would leave me with 50 l in the barrel.

This is also not acceptable.

Clearly there is some idiot trick that I just can't think of due to a lack of lateral thinking.

Isn't there some information missing here? Where should you obtain the 50 liters? I assume the big barrel. Do the amounts in each small container have to be the same in the end? any other rules? Probably what is meant is:

* 50 liters in the big barrel
* equal amounts of liters in the small containers in the end
* small container must be full when plunged in the barrel
* cannot pour from one containers into another (?)
* the 50 liters in the barrel is the beer that will be drunk

I think the trick is probably in the 10 "spare" liters that are left in the barrel

Fill up the three 15L containers until the 100L barrel is half-full?

Fill up all three containers. That is 45l. Drink it all. Fill up one container. Divide equally into the other two containers such that there are 5 l in each. Drink one of the containers. You have drunk a total of 45 L + 5 l = 50 l.

Wasn't this in one of the Bruce willis movies?

As far as I know you're not allowed to guess or estimate, so pouring 1/2 of one container isn't valid.

That's not allowed as you can't drink until you have 50L. (ie. drinking 45 first is not allowed!!!)

Another way is fill two of the containers. You have 60 L left in the barrel. Divide what's in the two containers so that they are equally distributed in the three containers. They have 10 L each in them. Pour from the large container and fill up two of the containers. You now have 50 L left in the barrel. Drink it.

Assumptions:

1) the beer you "obtain" is removed from the barrel into your containers
2) you can drink it as you "obtain" it
3) the containers are of thin material construction

Method

a) sink a 15l container completely within the barrel (without displaying further liquid). This will displace 15 litres causing an overspill of five litres from barrel into another of your containers. Drink this.

b) Fill up your three containers each of 15l for the the remaining 45l.

c) head down Stauffacher tramstop and consume outstanding.

dave

The riddle from Die Hard with a Vengeance was different involving different sized containers.

Die Hard 3

The one with a Brit playing a German baddie with a bad accent.........

What does "not acceptable" mean ? If the question given is as-written then anything that is not constrainted is acceptable including my solution and your two. Presumably the question was written by a psychologist rather than anyone with a reasonable grip on reality ?

dave

You can drink the beer once you have it. A key missing word may be "all", ie you can drink it once you have it all. In the absence of this word, provide your solution.

Incidentally I seem to remember a court case being fought on this very point - whether the "on receipt of it" distinguished between a complete order or partial delivery under the contract....

dave

Nope, by a pilot.

I concur with the displacement technique. Furthermore, it is usual custom for the smaller containers to be different sized, otherwise no actual change in quantity can take place... The beer has to be in the barrel, I guess, as it's the only space that will hold the 50 l.

tilt the barrel, pouring its contents into the 3 jugs...

.. as you are filling the third jug the barrel will start to become balanced on it's bottom steel hoop..

carefully add/remove beer until the barrel is perfectly balanced on it's edge.

you now have 50litres in the barrel.

I've now spent 10 minutes thinking about this.

Is there a valid answer?

We can get 5 litres in a jug through the displacement method, but this doesn't actually help since we actually need 10 l in a jug and the displacement method is only valid for jug 1.

Of course, a pilot. I should have remembered you mentioned it in one of your I'm-on-a-date-again posts.

Not sure what you mean by "usual custom" ? Do you normally procure 50l of beer at a time ? My kinda gal.

dave

I like the balance method, but guess it isn't the answer since not 100% accurate?

You lost me at beer and nuts...


Mmm beer.

Can the pilot confirm that?

The pilot (who was lying on a beach in St. Maarten when he sent this, b******) has been briefed with the tipping technique and the query re there actually being a solution. As it is currently early in the morning on the Netherlands Antilles, I doubt I'll get an answer any time soon...