Multiple choice

The average age of 24 boys in a class is 11, when the teacher's age is included the average increases by one. What is the age of the teacher?

  1. 34 years

  2. 42 years

  3. 36 years

  4. 48 years
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Total age of 24 boys = 24 x 11 = 264 years. New total including teacher = 25 x 12 = 300 years (since average increased to 12). Teacher's age = 300 - 264 = 36 years. This is a standard 'average of a group' problem - find totals before and after.

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