Multiple choice

The average age of 30 students and their teacher is 20 years. If the teacher is 50 years old, find the average age of only the 30 students.

  1. 15 years

  2. 18 years

  3. 19 years

  4. None of these
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Sum of ages of 30 students + teacher = 31 * 20 = 620. Sum of ages of 30 students = 620 - 50 = 570. Average age of 30 students = 570 / 30 = 19.

AI explanation

Using the formula Total Age = Average times Number of People, the total age for 31 people is 20 times 31 = 620 years. Subtracting the teacher's age of 50 years leaves 570 years as the total age of the 30 students. Dividing 570 by 30 gives the students' average age of 19 years. The result is 19 years.

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