There are 6 coins weighing 1, 2, 3, 4, 5 and 6 grams that look the same, except for their labels. The labels are supposed to display the weights of the coins.
How can you determine whether all the labels are correct,
using the balance scale only twice?
(In reply to short solution - spoiler
by Ady TZIDON)
That means there are at least two solutions. Perhaps my program would have found yours if I had allowed it to continue--as I said, it was a slow running program.
Worded the same as yours:
Let us weigh the coins labeled "1, 3" against the one labeled "5".
If the "5" is not heavier, the labeling is wrong.
Next weighing (needed only if first showed the 5 to be heavier): Weigh coins "1,2,5" against coins "3,6".
Iff (3,6) outweighs (1,2,5), all coins are labeled correctly.
Posted by Charlie
on 2016-01-13 19:29:50