you find 12 coins

eleven are real gold, one is fake

you know the fake weighs a bit less than the others

all you have to use is balance scale

what is the least number of times you could use the scale and still determine for certain in which coin is fake?

bigbrotheprodude Feb 21, 2019

#1**+4 **

I think since you know the fake weighs a bit less, it will take 3 tries...

place 6 on each side the lighter side has the fake

take the lighter side and place 3 on each side

the lighter side again will have the fake

place one of each of these 3 on opposite sides of the scale......if they balance the one NOT on the scale is the fake....

if they do NOT balance, the lighter side is the fake.

You COULD get lucky and pick two coins at random and one will weigh less ...if you luckily picked the fake...so in this case it would be ONE try would be the MINIMUM>

ElectricPavlov Feb 21, 2019

#1**+4 **

Best Answer

I think since you know the fake weighs a bit less, it will take 3 tries...

place 6 on each side the lighter side has the fake

take the lighter side and place 3 on each side

the lighter side again will have the fake

place one of each of these 3 on opposite sides of the scale......if they balance the one NOT on the scale is the fake....

if they do NOT balance, the lighter side is the fake.

You COULD get lucky and pick two coins at random and one will weigh less ...if you luckily picked the fake...so in this case it would be ONE try would be the MINIMUM>

ElectricPavlov Feb 21, 2019