Multiple choice

The average age of 120 members of a society is 60.7 years. By addition of 30 new members, the average age becomes 56.3 years. What is the average age (in years) of newly joined members?

  1. 38.7

  2. 37.2

  3. 38.3

  4. 36.5

  5. None of these
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A Correct answer
Explanation

The total age of the initial 120 members is 120 * 60.7 = 7,284 years. After 30 new members join, the total age of the 150 members is 150 * 56.3 = 8,445 years. The sum of the ages of the new members is 8,445 - 7,284 = 1,161 years, which gives an average age of 1,161 / 30 = 38.7 years.

AI explanation

The total age of the 120 original members is 120 times 60.7, which equals 7284. The total age of all 150 members is 150 times 56.3, which equals 8445. The total age of the 30 new members is 8445 minus 7284, giving 1161. Dividing this by 30 gives the new members' average age of 38.7 years.

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