Multiple choice

The average age of 10 students and their teacher is 15 years. The average age ofthe first seven students is 15 yr and that of the last three is 11 yr. What is the teacher'sage?

  1. 33 years

  2. 30 years

  3. 27 years

  4. 24 years

  5. 23 years
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The total age of the 10 students and teacher is 11 x 15 = 165 years. The first seven students contribute 7 x 15 = 105 years, and the last three contribute 3 x 11 = 33 years. The teacher's age is 165 - 105 - 33 = 27 years.

AI explanation

The total age of the 10 students and their teacher is 11 multiplied by 15, equaling 165 years. The sum of the ages of the first seven students is 7 multiplied by 15, which is 105 years, and the sum of the last three students is 3 multiplied by 11, equaling 33 years. The sum of all the students' ages is 105 plus 33, resulting in 138 years. The teacher's age is the total age minus the students' age, 165 minus 138, yielding 27 years.

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