Average age of a class of 40 girls is reduced by 1 year when 10 girls whose average age is 20 years, are discharged and 10 new girls are admitted find the average age of new comers?

• assume the average age of 40 girls were x initially
  according to that total age=40x
  now 10 girls with avg 20 are leaving
  their total age is 200
  the avg of 10 newcomers is y(assume)
  so,it can be written
  (40x-200+10y)/40=(x-1)[reduced avg ahe by 1]
  solving this we gety=16
  so avg age of newcomers will be 16
• 12 years agoHelpfull: Yes(43) No(0)
• The avg age of the new comers will be 16
  Let S be total age of 40 girls initially
  So avg age initially=S/40
  Let S1 be total age of the 10 new girls
  and total age of the girls that left=20*10=200
  So new avg age=(S+S1-200)/40
  and it is given,
  S/40-(S+S1-200)/40=1
  Solving,S1=160
  So avg age of new girls=160/10=16
• 12 years agoHelpfull: Yes(9) No(0)
• let avg age of 40 girls=x
  total age =40x
  total age after 10 girls joined=40(x-1)
  so req age of 10 new girls=40(x-1)-{40x-200} =160
  avg=160/10=16
• 12 years agoHelpfull: Yes(5) No(0)
• let x : avg of girls before
  y: avg age of new comers
  40(x)-10(20)+10(y)=40(x-1)
  giving y=16
• 12 years agoHelpfull: Yes(3) No(0)
• avg age of 40 girls is x, then total age 40x will be 40(x-1) if 10 girls with avg age 20 are discharged, i.e. 20*10=200 (total age) and 10 new girl (suppose with avg age y)are admitted, i.e 10*y total age.
  so the equation is now::
  40x-40=10*y-200+40*x
  so, y=160/10=16
  
• 12 years agoHelpfull: Yes(1) No(0)
• total age reduce by the discharging girl is 40.and 10 year is cause by them.so the average of the new commer is (200-30)/10=17 year
• 9 years agoHelpfull: Yes(0) No(0)
• 16
• 9 years agoHelpfull: Yes(0) No(0)