Solution to Puzzle #1
He puts a hole in the barrel to make it weigh less.
Rita is a cook at the local diner. When she makes the Wednesday night special, spaghetti, she adds three drops of oil and two drops of vinegar to the water for the pasta. One Wednesday, as she picked up the vinegar bottle she accidentally dropped and broke it. Salvaging the rest of the vinegar, she instructed the bus boy to put the vinegar in the same bottle as the oil.
How could Rita pour exactly three drops of oil and two drops of vinegar into the water using just one bottle?