*Originally posted by iamatiger*

**Yeah - realised that just after the option to edit the message expired ðŸ™‚ The second challenge where you don't know whether fools gold is light or heavy still stands though ðŸ™‚ The current best guess of 7 can be beaten significantly!**

Let me try. Number the balls 1 to 8.

l: means the balance goes to the left

r: the balance goes to the right

=: the balance stays horizontal

1H means ball 1 is heavier

1L means ball 1 is lighter

Round 1: 1 2 3 vs 4 5 6

a) if l: then round 2: 1 4 vs 2 5

a1) if l: then round 3: 1 vs 7

if l: then 1H

if =: then 5L

a2) if =: then round 3: 3 vs 7

if l: then 3H

if =: then 6L

a3) if r: then round 3: 2 vs 7

if l: then 2H

if =: then 4L

b) if =: then round 2: 1 vs 7

b1) if l: then 7L

b2) if r: then 7H

b3) if = then round 3: 1 vs 8

if l: then 8L

if r: then 8H

c) if r: then round 2: 1 4 vs 2 5

c1) if l: then round 3: 4 vs 7

if l: then 4H

if =: then 2L

c2) if =: then round 3: 3 vs 7

if =: then 6H

if r: then 3L

c3) if r: then round 3: 5 vs 7

if l: then 5H

if =: then 1L

I hope I didn't mess up. Allways 3 actions, except in one case where 2 suffice.