(In reply to re(2): Any thoughts on this one?
It is solvable with 97 COINS in 7(OR LESS) trials .
Initially I was presented with smaller numbers and erred in
"extrapolation" trying to publish a more difficult task.
OK - Start with picking randomly 2*13 marbles and compare one set of 13 with the other, If they balance your new problem is to continue w3ith 71 un-touched marbles within 6 or less steps..
If not, the lighter side may be seen as 6 pairs and ODD MAN OUT=compare within eachb pair..6 times at most.
Now it's up to you to continue the process and describe it in such details that I will copy it and paste as an official solution.
I hope you still like the puzzle. I certainly do.