Multiple choice

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

  1. $12$ years
  2. $10$ years
  3. $8$ years
  4. $14$ years
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A Correct answer
Explanation

The total sum of ages for 30 students is 30 * 12 = 360. The sum of the two groups is (5 * 10) + (5 * 14) = 50 + 70 = 120. The remaining 20 students have a total age of 360 - 120 = 240, so their average is 240 / 20 = 12.

AI explanation

The total age of all 30 students is 30 multiplied by 12, which equals 360 years. The combined age of the two groups of 5 students is (5 multiplied by 10) plus (5 multiplied by 14), totaling 120 years. The age of the remaining 20 students is 360 minus 120, which is 240, and dividing this by 20 gives an average of 12 years.

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