Multiple choice

The average age of 120 members of a society is 62.5 years. On adding 30 new members, the average age becomes 58.2 years, what is the average age of the newly added members?

  1. 40 years

  2. 41 years

  3. 39 years

  4. 42 years
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Total age of 120 members = 120 × 62.5 = 7500 years. After adding 30 members, total members = 150 and new total age = 150 × 58.2 = 8730 years. Age of 30 new members = 8730 - 7500 = 1230 years. Average age of new members = 1230/30 = 41 years. This is a weighted average problem where the new group has lower age, pulling down the overall average.

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