Multiple choice

Three years ago, the average age of a family of 5 members was 17 years. On adoption of a child to the family, the present average age of the family still remains the same. The present age of the child is:

  1. 3 years

  2. 1 year

  3. 2 years

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

3 years ago, sum of ages of 5 members = 5 * 17 = 85. Present sum of ages of these 5 members = 85 + (5 * 3) = 100. With the child, there are 6 members, and the average is still 17. Total sum = 6 * 17 = 102. Child's age = 102 - 100 = 2.

AI explanation

Three years ago, the total age of the 5 family members was 5 multiplied by 17, which is 85 years. The present total age of these original 5 members is 85 plus 5 multiplied by 3, resulting in 100 years. Let the child's present age be C; the new present total age for all 6 members is 6 multiplied by 17, which equals 102. Solving 100 + C = 102 gives the child's present age as 2 years.

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