How do you measure 4 liters with 5 and 7 liter containers?

Answer 1

Notes: There is most likely a more efficient way to do this, but this is the best I can do for now.

Notation: ( x , y ) where x is the amount of water in the 5-liter container and y is the amount of water in the 7-liter container

1. Fill the five-liter container ( 5 , 0 )

2. Pour the five-liter container into the seven-liter container ( 0 , 5 )

3. Fill the five-liter container ( 5 , 5 )

4. Fill the seven-liter container with the five-liter container, leaving 3 liters in the five-liter container ( 3 , 7 )

5. Pour out the seven-liter container ( 3 , 0 )

6. Pour the five-liter container into the seven-liter container ( 0 , 3 )

7. Fill the five-liter container ( 5 , 3 )

8. Fill the seven-liter container with the five-liter container, leaving 1 liter in the five-liter container ( 1 , 7 )

9. Pour out the seven-liter container ( 1 , 0 )

10. Pour the five-liter container into the seven-liter container ( 0 , 1 )

11. Fill the five-liter container ( 5 , 1 )

12. Pour the five-liter container into the seven-liter container ( 0 , 6 )

Answer 2

Fill the 7 liter, fill the 5 from the 7 leaving 2 in the 7. empty the 5 litre jug and add the 2 litres into the 5 litre jug. Fill the 7l jug and then fill the 5 litre jug again, which will leave you with 4 litres in the 7 litre jug as there was already 2 in the 5 litres (5-2=3 taken from the 7, 7-3=4)

Answer 3

Assuming you have a separate container to hold the 4 litres... Fill the 5 litre and empty it into the 8 litre. Repeat - and retain the 2 litres you have left when the 8 litre is full - pour that into the 'spare' container. Empty the 8 litres out and repeat the process again - you should now have 4 litres in your spare container.

Answer 4

I can do it, but you have to bring another unmarked bucket or jar to collect the 6 liters in. Steps: 1). Fill the 5 jar. 2). Empty the 5 jar into the 7 jar. Now you have 5 in the 7 jar. 3). Fill the 5 jar again. 4). Use it to slowly fill the 7 jar. That will take 2, and you'll have 3 left in the 5 jar. 5). Empty the 3 out of the 5 jar into your bucket. 6). Empty the 7 jar. Both the 5 jar and the 7 jar are empty now. 7). Repeat step-1 8). Repeat step-2 9). Repeat step-3 10). Repeat step-4. You have 3 in the 5 jar. 11). Add the 3 from the 5 jar into your bucket. You have 6 liters in your bucket. QED. This is probably not the answer you want, but it's the best I can come up with today. Anybody else out there ?

Answer 5

Fill up the seven liter cup cup and subtract 3 liters with the three liter cup and roughly add one liter.

Answer 6

Fill each jar half way. You will have 6 liters total.