A set of 17 coins contains five 35g coins and twelve 30g coins. Using a balance scale at most four times find at least two of the 35g coins.
My first try at solving any puzzles.<o:p></o:p>
Divide into two stacks of 8 and weigh. <o:p></o:p>
If balance, 2 35g coins in each stack and remaining coin is 35g. Divide 1 stack and weigh 4 vs 4. *If they balance each stack of 4 contains 2 35g coins. Take stack of 4 and compare 2 vs 2. Low side contains 2 35g coins. If balance 1 35g in 2 coins each side. Weigh to identify. If 4 vs 4 does not balance 3 or 4 35g coins in low stack. Compare 2 coins. Balance means both are 35g. Non balance identifies a 35g coin.<o:p></o:p>
If 8 vs 8 does not balance, 3 to 5 35g coins on low side. Take coins from low side and divide into 2 stacks of 4. Weigh. If balance proceed as from * above. If 4x4 does not balance 2, 3 or 4 coins in low stack. Weigh 2 of these coins. If balanced must be similar. Compare 2 vs 2 with the 2 unweighed coins from this stack. Balanced – all 4 are 35g. Non Balance – low stack contains 2 35g coins.<o:p></o:p>
First Attempt
