Question

The average age of 48 students of a class is 22 years. If the age of the teacher is also included, the average age of the whole group becomes 23 years. The age (in years) of the teacher is:

• A. 60
• B. 71
• C. 68
• D. 70

Answer 1

Answer:

B. 71

Average age of 48 students = 22 years

Total age of 48 students

$48 \times 22 = 1056$

Include the teacher

Now number of persons = (48 + 1 = 49)
New average = 23 years

$49 \times 23 = 1127$

teacher’s age

$\text{Teacher's age} = 1127 - 1056 = 71$

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The age of the teacher is 71 years