Question

There are 10 bags of golden coin. Each bag contains 100 coins; each coin is 10g weight. However, among of them, there is 1 bag with fake coins. The weight of the fake coin is 9g. We are allowed to use a kitchen scale only one time, how to figure out the bag contain the fake coin?
have fun.

Answer 1

only one weighing?

Answer 2

if the fake one is chocolate .... i got a solution :)

Answer 3

It's just for fun, I know, it's quite easy for you to get the answer XD

Answer 4

cant say i know what a kitchen scale is ... maybe a bathroom scale

Answer 5

what defines a "use"? put all the bags in and take them out one at a time until you get the one that only goes down by 9 insted of 10

Answer 6

but I don't know what is a bathroom scale. One more question, does bathroom need a scale? for what?

Answer 7

someplace to hang your limes i think lol

Answer 8

my grandma had a scale in the bathroom that i think was a time machine ....

Answer 9

the net is so bad, I stopped typing, but it shows I am typing still, hehehe

Answer 10

hahaha.

Answer 11

yeah, ghost typing is fun .....

Answer 12

about define the "use" , You can put something on the scale only 1 time, read the number only on that time.

Answer 13

for example, if you put a bag of coin on the scale, the hang shows you 100, that means the bag is 100g and you can no longer use the scale

Answer 14

impossible if we are only allowed to use the scale once

Answer 15

hihihi.. I am sorry, it's possible. friend

Answer 16

id just get the bathroom scale then ....

Answer 17

we can use the bathroom scale to find the lightest bag, then verify it with the kitchen scale

Answer 18

hahaha.. ok , you got my medal before you wrote this sentence.

Answer 19

take i coins from the ith bag (i=1,..,10) and weigh all the coins chosen

Answer 20

you won

Answer 21

Wait if you take one coin from each bag and you weigh all of them at once on the scale you get 99 grams, how does that help you pin point the 9 g coin?

Answer 22

bag1 ---1coin
bag2---2coins
bag3----3 coins
.......................
sum of them is 55 coins . It's supposed to weigh 550g
put all on the scale. If the scale shows 450 g, that means 5 fake coins there.
If the scale shows 449 g, that means 1 fake coin there
Therefore, you know which bag is a fake one

Answer 23

sorry 450 that means 10 fake coins there

Answer 24

Ingenious.

Answer 25

then i feel special...because it did come from by brain :)

Answer 26

@Zarkon if that's you in your pic I wouldn't be surprised.

Answer 27

@Zarkon yes you are.

Answer 28

i hve not looked at the solutions up there as much as i could avoid lol, i think u need to take coins out of the bags and distribute in a way to figure out with 1 weighing

Answer 29

oh i see the trick thats why its a kitchen scale

Answer 30

the actual weight will tell you enough information

Answer 31

hmmm dont tell me

Answer 32

I won't !! :) my friend is smart enough to figure out this stuff. hehehe....

Answer 33

i know!! okay

Answer 34

i must keep track of all the bags

Answer 35

take 1 coinn from first one
2 coinss 2nd one
3 coins 3rd one
and so on
there will be different weight for each weighing depending on which bag is the fake one

Answer 36

I know you will win. hehehe..... It's dan!!

Answer 37

if first bag is fake then 1 less than expected
if 2nd bag is fake 2 less than expected
if 3rd bad is gake 3 less than expexted
so 99 = bag 1 fake
98 = bag 2
97 = bag 3 and so on