Multiple choice

The average age of the students of a class is 22 years. 12 new students with an average age of 17 years join the class, thereby decreasing the average by 2 years. The original strength of the class was -

  1. 16

  2. 17

  3. 18

  4. 19
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Let original students = n. Total age = 22n. After 12 students join: new average = 20, new total = (n+12)×20. Also new total = 22n + 12×17 = 22n + 204. So (n+12)×20 = 22n + 204. 20n + 240 = 22n + 204. 2n = 36, n = 18. Set up the equation using weighted averages.

Keep practicing — related questions