Multiple choice

The average age of 24 boys and their teacher is 15 years. When the teacher's age is excluded, the average age decreases by 1 year. Find the age of the teacher.

  1. 38 years

  2. 39 years

  3. 40 years

  4. 41 years

  5. 50 years
Reveal answer Fill a bubble to check yourself
B Correct answer
AI explanation

The total age of the 24 boys and the teacher is 25 times 15, which equals 375 years. When the teacher is excluded, the average age of the 24 boys becomes 14 years. Their total age is 24 times 14, which equals 336 years. The age of the teacher is the difference between the total ages, 375 minus 336, resulting in 39 years.

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