A marketing company devised a methodology of spreading its message through one another. One person can tell it to 3 persons in 4 minutes and these three persons tell the other three persons each in further 4 minutes and the process continues so on. How many minutes will it take to spread the message to 2187 persons.

a)48 minutes b)24 minutes c)32 minutes d)28 minutes

• according to the given condition 3^1 + 3^2 + 3^3 + ........ = 2187
  or 3(3^x - 1)/(3-1) = 2187
  or 3(3^x - 1)/2 = 2187
  or 3^x - 1 = 2187*2/3 = 4374/3 = 1458
  or 3^x = 1459 so x = 6 to 7
  so total time taken = (6to7)*4 = 24 to 28 min
  but if we take only the last step persons then 3^x = 2187 so x = 7
  so time = 7*4 = 28 min
• 13 years agoHelpfull: Yes(6) No(2)
• Option d
  1 person tells 3 persons in , 4 min
  3p will tell to 3*3 =9 in, 4 min
  9p will tell to 9*3= 27 in , 4 min
  27p will tell to 27*3= 81 in , 4 min
  81p will tell to 81*3= 243 in , 4 min
  243p will tell to 243*3 = 729 in , 4 min
  729p will tell to 729*3=2187 in , 4 min
  
  therefore total time = 28 min
  
  
  
• 8 years agoHelpfull: Yes(2) No(0)