Question

In a group of 9 coins, one is fake and weighs slightly less. What is the fewest number of times you need to use a pan balance to find the counterfeit coins? (A pan balance is a scale used to measure weights, where weights are placed in two pans. The heaviest
pan will go down and the other pan will go up.)


9 Coins total and 8 are equal weight.

1st weight time=

(LEFT): 1,2,3 (Right): 4,5,6 7,8,9

2nd Weight time= 1,2 6,7 8,9

=2 times to use a pan.

Answer 1

1234 against 4567 if equal, 9 is fake
then 1234 against 5679
take th low side
xxafainst yy
take the low side
z vs other ...4 trials max