The average age of 28 students in a group is 12 years. When teacherâ€™s age is included to it, the average increases by one. What is the teacherâ€™s age in years?	Choose the correct answer:
A) 31  B) 36  C) 41  D) 51  E) None
Sol.   Age of the teacher = ( 29 Ã— 13 â€“ 28 Ã— 12 ) years = 41 years.   Answer 41
<result>C</result>
The average age of 28 students in a group is 12 years. When teacherâ€™s age is included to it, the average increases by one. What is the teacherâ€™s age in years?