Find, in only one measurement, which bag contains the fakes.

Solution

Same question but among the 10 bags, two bags contain fake coins.

Solution

Same question but there is one bag of 9g coins and one bag of 11g coins.

Solution

Same question but I don't now how many 9g and 11g coins bags.

Be kind : I just have 5 bags, because with 10 bags the solution is not realistic.

Solution
Why just 5 bags ?