The average age of a family of 6 members is 22 years. If the age of the youngest member be 7 years, then what was the average age of the family at the birth of the youngest member?

• 18 yrs
  
  The average age of a family of 6 members is 22 years.
  Total age now = 22*6=132 years
  
  If the age of the youngest member be 7 years,
  Total age of 5 members 7 years ago = 132 -6*7 = 132-42 = 90 years
  then the average age of the family of 5 members just before the birth of the youngest member = 90/5 = 18 yrs
  the average age of the family of 6 members just after the birth of the youngest member = 90/6 = 15 years
• 12 years agoHelpfull: Yes(14) No(4)
• 18 is the average age of the family just before the birth of the youngest member.
  
  
  Total Sum of the ages of family = 132 years now. (i.e., 6*22= 132yrs)
  
  At the birth of the youngest member means 7 years earlier,
  
  At that time the sum of the ages is 132-(7*6) years. (because of the presence of 6 members)
  
  So the sum of the ages =90 and
  Average is 90/5 = 18(because one of the members is not there)
• 12 years agoHelpfull: Yes(5) No(0)
• Sum of the ages of 6 members=22*6=132
  At the time of birth of the youngest memberi.e 7 years ago,sum of the ages=132-7=125=sum of the ages of five members
  Therefore, Average of the age of five family members=125/5=25
• 12 years agoHelpfull: Yes(4) No(9)
• 12 is the average age of the family at the birth of the youngest member.
  
  
  
  Total Sum of the ages of family = 132 years now. (i.e., 6*22= 132yrs)
  
  At the birth of the youngest member means 7 years earlier,
  
  At that time the sum of the ages is 110-(7*6) years. (because of the presence of 6 members)
  
  So the sum of the ages =68 and
  Average is 60/5 = 12(because one of the members is not there)
• 12 years agoHelpfull: Yes(1) No(6)
• {50(1),10(5,4,3,2,1,0),1(7)}=6 cases
  50(2),10(0),1(7)=1
  50(0),10(1,2,3,4,5,6,7,8,9,10),1(7)=10 cases
  50(0),10(0),1(107)=1
  total =18 cases
• 9 years agoHelpfull: Yes(1) No(0)