Question

If the mean age of 30 students of a class is 10 years. If the age of their teacher is also included than the mean is increased by 1 year. What is the age of the teacher?​

Answer 1

Soln. :

Average age of 30 students=9

Total age of 30 students = 30 ×9=270 (1)

Average including teacher (31 person, 30 students + 1 teacher) =10

Total age including teacher=31×10=310

Age of 30 students + age of teacher =310

By(1) Replace Age of 30 students with 270

270 + Age of teacher = 310

Age of teacher =310–270=40. Ans….