Multiple choice

The average age of $12$ children is $20$ years. If the age of one more child is added, the average is decreased by $1$. What is the age of the child added later ?

  1. $9$ years
  2. $8$ years
  3. $7$ years
  4. $6$ years
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Initial sum of ages = 12 * 20 = 240. New sum with 13 children = 13 * 19 = 247. The age of the added child is 247 - 240 = 7 years.

AI explanation

The total age of the initial 12 children is 12 multiplied by 20, which equals 240 years. When the new child is added, the average age decreases to 19 years for the 13 children. The new total age becomes 13 multiplied by 19, which is 247 years. The age of the added child is the difference between the new total and the old total (247 minus 240), resulting in 7 years.

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