Find the 9 gram marbles riddle
March 8, 2007 4:16am CST
There are ten bags containing marbles. Each bag has at least 10 marbles in it. Nine of the bags contains only marbles weighting 10 grams each. One of the bags contains only marbles weighing nine grams each. Each bag has a different number of marbles in it. All of the marbles look exactly the same. The riddle is how can you know which bag has the nine gram marbles if the only device allowed to be used is a weighing scales which you can use only once?
• United States
8 Mar 07
number the bags from 1 to 10 and put the 10 bags in a row, take one marble from one bag, then 2 from the second bagm 3 from the third bag, etc. Place all 55 marbles on the scale, the number of grams of the total weight that differs from 550grams..which would be the total of 55 marbles at 10 grams each... is the amount of marbles taken from the bag that contains the 9 gram marbles.. example : weight of the 55 marbles = 523 grams 550-523 = 27 9 x 3 = 27 bag #3 you extracted 3 marbles bag #3 contains the 9 gram marbles