3022 A riddle

You are given 5 bags. There are 10 beads in each of the bags. In four of the bags, the beads each weigh 10 kilograms. In the remaining bag, each bead weighs only 9 kilograms. All the bags and beads look identical. You must find out which bag has the lighter beads. The problem is that all the bags look identical and all the beads look identical. You can use a scale, but it has to be a single-tray scale, not a two-tray balance scale. Also, you may use the scale only once. How can you find out which bag has the lighter beads?

Category
Circolo di Conversazione

Submitted by Anonymous (not verified) on Wed, 03/22/2006 - 12:53

tinks ! not very good at riddles but i will have a go....... its got to be last bag you put on scales because each bag you put on scales weighs 100gm and last bag will weigh 90gm even though it may contain 10 beads,total weight is 490gms, you are putting one bag on at a time...or have i totally lost the plot:eek:

Submitted by Anonymous (not verified) on Wed, 03/22/2006 - 13:09

Tinks,
Put all 5 bags(490kg) on scales & take them off one at a time. The first bag to register only a 90kg reduction is your bag - hold on i can't lift that much!,
(Tinks, you've got to get out of your bedroom, off the computer & get out more kid).

Submitted by Anonymous (not verified) on Wed, 03/22/2006 - 14:47

Rob..

Did you really think Tink would give you such an easy riddle? Did you forget you can only use the scale ONCE? Your way.. you actually use the scale five times!! :D

It took Aliena 8 minutes to work it out..

You have to number the bags from 1 - 5.. take 1 bead out of bag 1. Then.. take 2 beads out of bag 2. Take 3 beads out of bag 3 and do the same thing with bags 4 and 5. Put all these 15 beads on the scale.. therefore, using it only once!

We already know if all 15 beads weighed 10 kilos each.. the scale would show 150 kilograms.. but since one or more of the beads weighs only 9 kilos, the scale will show less than 150 kilos.

Subtract the number on the scale from 150. Your answer will tell you the number of the bag with the lighter beads.

If the scale shows a weight of 148 kilos.. then it’s bag number 2. If the scale registers 145 kilos.. then it’s bag number 5 etc., etc.

:D :D

Submitted by Anonymous (not verified) on Wed, 03/22/2006 - 19:29

Aliena Cara,
...but i HAVE used the scales only once, i am just taking the weights off slowly, can you not see amore?

Submitted by Anonymous (not verified) on Wed, 03/22/2006 - 19:34

Rob.. scarrafaggio mio :D

You should know better than to argue with Aliena.. so stop whinging and admit you were wrong.. it will be less painful for you in the end. ;)

:) :)

Submitted by Anonymous (not verified) on Wed, 03/22/2006 - 19:42

.....oh the pleasure, oh the pain. I might want to stay wrong OK Boss lady?

Submitted by Anonymous (not verified) on Wed, 03/22/2006 - 19:44

Si.. va bene.. so long as we know it was your choice! :D :D

:) :)

Submitted by Anonymous (not verified) on Wed, 03/22/2006 - 19:52

...i've been down the pub, i'm not bothered, whip or birch, your choice tough guy.

Submitted by Anonymous (not verified) on Thu, 03/23/2006 - 03:06

My choice.. is a wooden spoon! :p

:) :)

PS. sono imbroglione. :D

Submitted by Anonymous (not verified) on Thu, 03/23/2006 - 03:16

Sounds as though Tinks might be copying and pasting questions from his GMAT practice tests but he is wasting his tme as you are not permitted to contact the forum during an exam. :rolleyes:

Submitted by Anonymous (not verified) on Thu, 03/23/2006 - 03:31

As usual, Aliena is correct. Almost. She has failed to honour Tinker's law. :)

Puglia self together Rob...Aliena is too busy with her googling to sort you out proper ;)