The average age of a class of 19 students is 20 years. The average increased by 1 when the teacher's age also included. What is the age of the teacher? Choose the correct choice from the following.
A) 39
B) 41
C) 40
D) 42
E) 43
Total age of all students =19Ã—20   Total age of all students + Age of the teacher =20Ã—21   Age of the teacher   =20Ã—21âˆ’20Ã—19=20(21âˆ’19)=20Ã—2=40   Answer is 40.
<result>C</result>
The average age of a class of 19 students is 20 years. The average increased by 1 when the teacher's age also included. What is the age of the teacher?