Q1: What is the average age of children in the class?  I. The age of the teacher is as many years as the number of children.  II. Average age is increased by 1 year if the teacher's age is also included.

ANS:D - Both I and II are not sufficient to answer

Let there be x children. I gives, age of teacher = x years. II gives, average age of (x + 1) persons = (x + 1) years.  Teacher's age = (x + 1) (x + 1) - x² = (x² + 1 + 2x) - x² = (1 + 2x) Thus, teacher's age cannot be obtained.  Correct answer is (D)