In 80 coins one coin is counterfeit what is minimum number of weightings to find out counterfeit coin?

• divide 80 into 2 parts i.e 40 each.. then put them on two sides of balance. the one weighing less or more would contain the counterfeit coins .. divide 40 into 20 each and do the same .. divide 20 into 10 each and do the same.divide 10 into 5 each and do the same divid esame now. now we have 2 coins each and one extra so anso ,if two coins weigh same .. the extra is our coin..if they weigh so diggfernt .. do the same.. so ans.is 5 or 6
• 13 years agoHelpfull: Yes(21) No(3)
• 4 weightings required. Till 3^n coins, n+1 weightings required to find the counterfeit coin.
• 13 years agoHelpfull: Yes(7) No(6)
• what is counterfeit?
  
• 13 years agoHelpfull: Yes(7) No(7)
• COUNTERFEIT MEANS "HAVING LESS OR MORE THAN ACTUAL WEIGHT".
• 13 years agoHelpfull: Yes(6) No(3)
• first make 8 groups wid 10 coins each n take weights
  one group will hav different weight
  take that group n divide into 3 groups 3 coins each and u hav one coin remaining
  take weights of 3 groups if they are equal the other one coin remaining is the counterfeit and the ans becomes 8+3=11
  but if they are nt equal the again take that group of coins which hav diff weight n measure weight of 3 coins 2 coins will hav some weight n other one coin will hav different weight and that is counterfeit.
  so total 8+3+3=14 is the ans
• 13 years agoHelpfull: Yes(1) No(11)