Multiple choice

The average age of a class of 30 students is 14 years. If the age of the teacher is included, the average age becomes 15 years. What is the teacher's age?

  1. 59

  2. 45

  3. 32

  4. 26

  5. NONE OF THESE
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Total age of 30 students = 30 * 14 = 420. With the teacher, there are 31 people and the average is 15, so total age = 31 * 15 = 465. Teacher's age = 465 - 420 = 45.

AI explanation

Using the average formula, the total age of the 30 students is 30 times 14, which equals 420 years. When the teacher is included, the total age becomes 31 times 15, which equals 465 years. The teacher's age is the difference between these two totals, so 465 minus 420 equals 45 years. The teacher is 45 years old.

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