Question:
The average age of 20 students is 12 years. If the teacher's age is included ,average increases by one. The age of the teacher is
A30 years
B33 years
C32 years
D35 years
Answer:
B. 33 years
Explanation:
Average of 20 students = 12 years Total age of 20 students = 20 × 12 = 240 years When teacher included average become 13 years Now, total age 20 students and teacher = 13 × 21 = 273 years ∴ Age of teacher = 273 - 240 = 33 years