Q392
The average age of 30 students is 9 years. If the age of their teacher is included, the average age becomes 10 years. The age of the teacher (in years) is :
A.
27
B.
31
C.
35
D.
40
AnswerAnswer: Option D
Solution
Answer: Option D
Solution:
Let the age of teacher = x yearsAccording to the question,
30 × 9 + x = 31 × 10
270 + x = 310
x = 40 years