There is a 5 gallon and a 3 gallon bottle. You also have a hose with unlimited water. How are you gonna make the 5 gallon have 4 gallons using your items?
(You don't know the exact dimensions of a gallon)
You fill the five gallon up and pour it into the 3 gallon. The dump the 3 gallon out and pour what was left in the 5 gallon into the 3 gallon so that you have 2 gallons in the 3 gallon. Then fill the 5 gallon up and pour it into the 3 gallon to fill it up. Now you have 4 gallons in the 5 gallons.
It can't be seen, can't be felt, can't be heard and can't be smelt. It lies behind stars and under hills, and empty holes it fills. It comes first and follows after, ends life and kills laughter. What is it?
We have two soap of equal weights and a 3/4 pound weight.
However, after using 1/4 of soap we place all three objects on balance as On one side of balance we place one soap (unused) and on another side, we placed used soap (i.e 3/4th of soap) and 3/4 pound weight.
What is the soap weight?