Multiple choice

The average age of 40 students in a group is 15 years. When teacher's age is included the average increases by one. What is the teacher's age ?

  1. 56 years

  2. 57 years

  3. 59 years

  4. 58 years
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A Correct answer
Explanation

Average age of 40 students = 15 years, so total age = 40 × 15 = 600 years. When teacher is included, average of 41 people = 16 years (increased by 1), so total age = 41 × 16 = 656 years. Teacher's age = 656 - 600 = 56 years.

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