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# Math

+1
49
2

There are 15 gold coins. One of the gold coins is a fake. A fake gold coin is lighter than a real one. You have a “balance machine” without any scale. Can you identify the fake coin by using the “balance machine” at most three times?

Apr 6, 2021

#1
+31287
+2

Yes you can....is that what you wanted.....or an explanation as to how?

Starts this way   make 3 piles  7   7    1

balance the 7's    if they balance, then the '1' is the fake

if they DON't balance, the lighter 7 has the fake

take the lighter 7   make 3 piles   3  3  1

balance the 3's   if they balance then the '1' is the fake

if they don't balance then the lighter 3 has the fake

take the lighter 3     make 3 piles  1  1   1

balance two of the 1's

if they balance , the third '1' is the fake

if they don't balance , the lighter one is the fake .....with only THREE balances done !

Apr 6, 2021

#1
+31287
+2

Yes you can....is that what you wanted.....or an explanation as to how?

Starts this way   make 3 piles  7   7    1

balance the 7's    if they balance, then the '1' is the fake

if they DON't balance, the lighter 7 has the fake

take the lighter 7   make 3 piles   3  3  1

balance the 3's   if they balance then the '1' is the fake

if they don't balance then the lighter 3 has the fake

take the lighter 3     make 3 piles  1  1   1

balance two of the 1's

if they balance , the third '1' is the fake

if they don't balance , the lighter one is the fake .....with only THREE balances done !

ElectricPavlov Apr 6, 2021
#2
+118470
0

Impressive, EP!!!!!

CPhill  Apr 6, 2021