The average age of 30 students is 15 years. It was observed that while calculating the average age, the age of a student was taken as 15 years instead of 9 years. What will be the correct average  age ?

14.8 years

Sum of ages of 30 students = 30 x 15 = 450

Sum of ages after correction = 450 - 15 + 9 = 444

Correct average = \(\frac{444}{30}\) = 14.8 years