Average weight of 45 students in a class is 52kg.5 of them leaves the class whose average weight is 48kg.another 5 of them join the class whose avg weight is 54 kg.what is the new average weight in the class?

• ans:522/3 i.e 52.66
  if avg of replacing group is same as leaving group avg will not be changed.
  but avg is more by 6, then more sum will be 30
  then new avg will be 52+30/45=52.66
• 10 years agoHelpfull: Yes(2) No(0)
• the total weight initially was = (45*52)
  the weight of the boys left =(5*48)
  the weight of the boys joined=(5*54)
  the resultant weight is = (45*52)+(5*54)-(5*48)
  =(45*52)+5(54-48)
  = (45*52) + 5*6
  = 5(9*52+6)
  the average weight is = {5*(9*52+6)}/45
  = 474/9 = 158/3 = 52.66 kg .
• 10 years agoHelpfull: Yes(0) No(0)