How can you measure 4 litres with two buckets and a tap?

[mia5]

You have got two buckets of capacity 3 litres and 5 litres each and a tap. How will you exactly measure out 4 litres of water with the help of two buckets and the tap.

 

[Kholdstare]

You fill up 5 liter one from the tap. Then fill up 3 liter one from 5 liter one. Then empty the 3 liter one. Then split what's left in 5 liter in two buckets. Then fill up the 3 liter one again and pour it into the 5 liter one.

 

[jedishrfu]

1) fill the 5 liter and pour into the 3 liter until full leaving 2 liter in the 5 liter bucket.

2) empty the 3 lt bucket and pour the remaining 2 lt from the 5 lt bucket into the 3lt.

So the 3 liter bucket now has 2 liters in it.

3) Lastly fill the 5 liter completely and then pour it into the 3liter bucket until the 3 liter bucket is full.

Since the 3 liter bucket had 2 liters in it then you've out 1 liter so that what remains in the 5 liter bucket is 4 liters.

 

[Danger]

I'd calculate the height of 4 litres in the confines of the 5 litre bucket, then draw a line at that point and fill to there using the 3 litre bucket as a source.

 

[jedishrfu]

I'd calculate the height of 4 litres in the confines of the 5 litre bucket, then draw a line at that point and fill to there using the 3 litre bucket as a source.

so we have the OP solution: ask someone on PF

and the caveat emptor solution: kholdstare's split the difference

and the greek solution (compass and straight edge only): mine

and the high-tech engineering solution: Danger's

we still need a management solution and a CEO solution to complete the picture.

Of course VP Biden could step in at anytime with a shotgun solution but we won't consider that option for now :-)

 

[Curious3141]

so we have the OP solution: ask someone on PF

and the caveat emptor solution: kholdstare's split the difference

and the greek solution (compass and straight edge only): mine

and the high-tech engineering solution: Danger's

we still need a management solution and a CEO solution to complete the picture.

Of course VP Biden could step in at anytime with a shotgun solution but we won't consider that option for now :-)

Management solution: Set up an interdepartmental cross-disciplinary committee with broad terms of reference to study the problem. Outsourcing is an acceptable option, preferably to a third world country where buckets, natural water sources and cheap labour are already plentiful, obviating the need for a budget to procure these.

CEO solution: CEO admits to not being able to solve the problem, and not even having foreseen that such a problem might exist. Therefore, regretfully, the CEO immediately resigns, accepting the previously agreed-upon golden parachute to the tune of $50 million USD and another plum CEO job offer in a rival company.

 

[Danger]

I will mention two caveats to my answer.
1) It was partially a management response because there is no need for the 3-litre bucket, but since it's there it must be used.
2) It was purely theoretical because I have absolutely no idea of how to do the math.

 

[Office_Shredder]

The Apple solution is to insist the 3 liter bucket is good enough and if you aren't getting 4 liters of water from it it's because you're holding it wrong

 

[Curious3141]

The Apple solution is to insist the 3 liter bucket is good enough and if you aren't getting 4 liters of water from it it's because you're holding it wrong

They also insist that you fill it only with Apple^TM water otherwise all warranty coverage on the bucket is void.

 

[Danger]

if you aren't getting 4 liters of water from it

But that won't happen.

 

[ImATrackMan]

They also insist that you fill it only with Apple^TM water otherwise all warranty coverage on the bucket is void.

Using a special hose attachment that splits the stream and shapes it into two hexagons because, for whatever reason, a standard "circular" stream isn't as efficient.

 

[Danger]

Using a special hose attachment that splits the stream and shapes it into two hexagons because, for whatever reason, a standard "circular" stream isn't as efficient.

Do I see a patent for a spin-off from condom technology in your future? Maybe a urinal-based game of some sort?

 

[Charmar]

You have got two buckets of capacity 3 litres and 5 litres each and a tap. How will you exactly measure out 4 litres of water with the help of two buckets and the tap.

This may prove to be useful in visualising your answer.

www.youtube.com/watch?v=lZ64IR2bz5o

 

[Curious3141]

This may prove to be useful in visualising your answer.

www.youtube.com/watch?v=lZ64IR2bz5o

I thought of this movie too - I remember this scene very well (along with the Saint Ives riddle).

There are multiple solutions, of course. I think I found 3.

 

[ImATrackMan]

Do I see a patent for a spin-off from condom technology in your future? Maybe a urinal-based game of some sort?

pffft... no! Whatever could have made you think that?

 

[Danger]

Whatever could have made you think that?

Nothing in particular. My mind wanders sometimes...

 

[ImATrackMan]

Also, one solution.

Spoiler

Fill the five liter bucket completely

Pour out three liters (where else?)

Fill the 5 liter bucket to twice the level of the remaining water (assuming it's perfectly cylindrical).

 

[Danger]

That's pretty clever, Mr. Trackman, but... have you ever seen a cylindrical bucket?
My uncle owned a bucket store... I had to make buckets every day after school... we made wood buckets and steel buckets and I even made one out of a dead badger once... and I got to tell you that not a single one of 'em was cylindrical.

 

[ImATrackMan]

That's pretty clever, Mr. Trackman, but... have you ever seen a cylindrical bucket?
My uncle owned a bucket store... I had to make buckets every day after school... we made wood buckets and steel buckets and I even made one out of a dead badger once... and I got to tell you that not a single one of 'em was cylindrical.

The internal (or external, for that matter) shape of the bucket was never specified, though!

 

[Danger]

Oh, sure... get technical about it...

 

[WCOLtd]

Spoiler

fill up the 3 liter bucket, pour it into the 5 liter bucket, then fill up the 3 liter bucket again and pour it into the 5 liter until the 5 liter bucket is full. Empty the 5 liter bucket pour the remaining 1 liter from the 3 liter bucket and then fill the 3 liter bucket and fill the 5 liter bucket, the water in the 4 liter bucket is exactly 4 liters.

 

[DaveC426913]

Mathematician's Answer:

Using decanting principles.
As this is a well-understood method for solving such a problem, the details are left to the reader.

 

[davenn]

Spoiler

fill up the 3 liter bucket, pour it into the 5 liter bucket, then fill up the 3 liter bucket again and pour it into the 5 liter until the 5 liter bucket is full. Empty the 5 liter bucket pour the remaining 1 liter from the 3 liter bucket and then fill the 3 liter bucket and fill the 5 liter bucket, the water in the 4 liter bucket is exactly 4 liters.

There is no 4 litre bucket !

 

[WCOLtd]

There is no 4 litre bucket !

Well I meant to say 5 liter bucket.