Average Practice Test 1

Average age of 30 boys in the class = 10 years
Total age of 30 boys = 10 × 30 = 300 years
According to the statement,
When the age of the teacher is included, then, average age will be 31 years.
So, the total age of boys and teacher = 31 × 11 = 341
Age of teacher = Total age of boys and teachertotal age of boys = 341 -300 = 41 years