There are 6561 number of balls in a bag. Out of which one is heavy ball. In how many minimum number of weighing you can find the heavy ball.

• Arithmitically it'l be solved in 8 minimum weighings.
  
  Expln:6561 balls. if u notice is 3^8..n can be divided by 3(prime factor) only...we keep on dividing it into sets of 3 and in 1 weighing itself you can determine which set is heavy.
  Divide that set into further 3 lots...keep doing that like,
  6561
  2187 2187 2187 1st weighing
  729 729 729 2nd weighing
  243 243 243 3rd weighing
  81 81 81 4th weighing
  27 27 27 5th weighing
  9 9 9 6th weighing
  3 3 3 7th weighing
  1 1 1 8th weighing
  
  So, it would be 8 attempts
  
• 13 years agoHelpfull: Yes(54) No(3)
• 8
  Divide into three groups... Weigh any one against any other... We can find the group to which the heavy ball belong... (If the two groups being weighed balances, then it is the third group. Else, it is the heavy group)... Repeat the procedure with the group containing heavy ball...
• 13 years agoHelpfull: Yes(9) No(4)
• Logically balls be of bigger,smaller and heavy(weighted either small/big) so which is of 3 categories. Now for given no. 6561 u can divide it by 3 until u get the remainder as 0
  As: 6561/3=2187
  2187/3=729
  729/3=243
  243/3=81 till here we got 4 times and to save time think 81 can be divided into 9*9 which is of 3^4 so, in total there will be 8 is the min.
  
• 10 years agoHelpfull: Yes(5) No(0)
• sorry, by mistake
• 10 years agoHelpfull: Yes(2) No(5)