The average age of 30 students in a class is 9 years.If the teacher's age includes an average of 10 years then what is the teacher's age

• no. of person = 30
  average age = 9
  then total age = 30*9 = 270...............(previous total age)
  after including teacher no. of person = 31
  average age = 10
  then total age = 31*10 = 310..............(new total age)
  
  difference = 310-270 = 30...ans.
  the age of teacher = 30 year.
• 11 years agoHelpfull: Yes(0) No(3)
• x/30=9
  then x= 270
  y is the age of teacher
  (x+y)/31=10
  (270+y)=310
  so,
  y=40 ans...
• 11 years agoHelpfull: Yes(0) No(0)
• sorry
  ans. is 40 year.
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• 40 Years...
  
• 11 years agoHelpfull: Yes(0) No(0)
• sum of ages of students= 30*9 = 270
  let teacher's age be x
  x+270=31*10
  x=310-270=40
  therefore, teacher's age is 40
• 11 years agoHelpfull: Yes(0) No(0)