Brain Teasers
Gold Bars
There was a millionaire who loved collecting gold. He bought ten solid gold shapes from a man, but the man proposed a bet. He said:
"One of these shapes is fake. It is made from a metal that looks exactly like gold. The only difference is that it is 1 gram lighter per 10 cubic cm. If you can find the fake, you can have all of the bars for free".
So the man weighed all of the bars, and to his surprise, they all weighed the same. Because of their strange shapes, he could not simply measure them. How can the man discover the fake without any measuring tools?
"One of these shapes is fake. It is made from a metal that looks exactly like gold. The only difference is that it is 1 gram lighter per 10 cubic cm. If you can find the fake, you can have all of the bars for free".
So the man weighed all of the bars, and to his surprise, they all weighed the same. Because of their strange shapes, he could not simply measure them. How can the man discover the fake without any measuring tools?
Answer
He could fill a bucket with water and place each shape in separately. Then whichever makes the water level rise most is the fake, as it would have to be slightly bigger to make it weigh the same.Hide Answer Show Answer
What Next?
View a Similar Brain Teaser...
If you become a registered user you can vote on this brain teaser, keep track of which ones you have seen, and even make your own.
Solve a Puzzle
Comments
i got it! we jsut studied the water displacement method in school!
like it!!
riddle mistakenly uses area (cm sq) where it should be volume (cubic cm) seller's hint makes no sense otherwise.
nice one
It is simple density porblem.... is that what I'm learning in school..........
I think that Archimedes figured out that problem over 2000 years ago.
wow that was really easy
I like it
I like it
nice teaser!!!!
This is Archamedes! Duh!
Basic Physics.
This one you either know right away, or you don't cause you have yet to take physics. The only problem I had with it was the fact you assume that a bucket (or any holder) of water would not be thought of as a tool. Sadly, in your solution, you are using the bucket exactly as a tool to measure the density of the objects.
i bet if you were alive 2000 years ago curtiss, you would have figured it out too right?
do you think your really smart?
i don't.
the answer to this teaser is DENSITY...that's all you had to write
do you think your really smart?
i don't.
the answer to this teaser is DENSITY...that's all you had to write
er would it also be possible to test the hardness of the gold with your fingernail? most metals are not soft enough to dent simply by pushing on them, but solid gold is. correct me if i'm wrong.
otherwise that was a really good teaser!
otherwise that was a really good teaser!
NICE.
correct me if i'm wrong, but size has nothing to do with it-density does.
The fake would be less dense, so even if it weighed the same, it would displace less water. Example: pumice floats because it is not very dense. drop a sample of gold of the same mass, and the gold would both sink and displace more water.
The fake would be less dense, so even if it weighed the same, it would displace less water. Example: pumice floats because it is not very dense. drop a sample of gold of the same mass, and the gold would both sink and displace more water.
You said "1 gram lighter per 10 sq cm" but you should have said 1 gram lighter per 10 *cubic* cm.
What kind of idiot offers a bet that he can lose but never win?
To post a comment, please create an account and sign in.
Follow Braingle!