Question 10
There is one counterfeit coin among 2019 identical-looking coins. The genuine coins have the same weight while the counterfeit coin is lighter. Andy wants to determine the counterfeit coin using a balance scale. There are no restrictions on the number of coins placed on the pans each time. What is the least number of weighings needed to find the counterfeit coin?
Interpretation: “Needed” means sufficient in the worst case. The counterfeit is known to be lighter.
Interpretation: “Needed” means sufficient in the worst case. The counterfeit is known to be lighter.