I have recently been attending a few interviews and had faced such questions in a well know company.
I got the above mentioned question of finding a less wieghing defective ball from 16 balls. I knew the answer.
Another question was to find a date closest to the given date (lesser than given date) which when represented in a
string is a palindrome. The given date was 10022001 (02 Oct 2001).When I started writing the logic to program it he told me to ifnd it manually. Even after 15 minutes and a couple of hints I did not get it
The interviewer was kind enough to explain me the answer and it was based on the logic ofelimination.
Fortunately, I managed to just clear it.
P.S : If anyone can provide me links to such questions I would like to try it out.
Regards