Multiple choice

The average age of 9 students and their teacher is 16 yr. The average age of the first four students is 19 yr and that of the last five is 10 yr. The teacher's age is

  1. 28 yr

  2. 30 yr

  3. 36 yr

  4. 34 yr
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Total age of 10 people (9 students + teacher) = 16 * 10 = 160. Total age of first 4 students = 19 * 4 = 76. Total age of last 5 students = 10 * 5 = 50. Teacher's age = 160 - (76 + 50) = 160 - 126 = 34.

AI explanation

Using the basic average formula, the total age of the 9 students and their teacher is 10 multiplied by 16, which equals 160 years. The total age of the first four students is 4 multiplied by 19, equaling 76 years, and the total age of the last five is 5 multiplied by 10, equaling 50 years. The combined age of these nine students is 76 + 50 = 126 years. Subtracting this from the overall total gives the teacher's age of 160 - 126 = 34 years.

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