Multiple choice

The average age of 30 students of a class is 12 years. Out of the 30 students, the average age of a group of 5 students is 10 years, and that of another group of 5 students is 14 years. What is the average age of the remaining students?

  1. 8 years

  2. 10 years

  3. 12 years

  4. 14 years
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C Correct answer
Explanation

Total age = 30 * 12 = 360. Sum of 5 = 5 * 10 = 50. Sum of another 5 = 5 * 14 = 70. Remaining 20 students = 360 - 120 = 240. Average = 240 / 20 = 12.

AI explanation

Using the basic average formula, the total age of all 30 students is 30 times 12, which equals 360 years. The total age of the two groups of 5 students is (5 times 10) plus (5 times 14), giving 120 years. The total age of the remaining 20 students is 360 minus 120, resulting in 240 years. Dividing 240 years by 20 students gives an average age of 12 years.

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