The average age of 39 students in a group is 10 years. When teacher’s age is included to it, the average increases by one. What is the teacher’s age in years? Select the correct option:  A) 50  B) 55  C) 60  D) cannot be determined  E) None of these
Age of the teacher = (40 × 11 – 39 × 10) years   = 50 years.   50nswer 50
<result>A</result>
The average age of 39 students in a group is 10 years. When teacher’s age is included to it, the average increases by one. What is the teacher’s age in years?