3 years age, the average age of a family of 5 members was 17 years. A baby having been born, the average age of the family is same today. The present age of the baby is :
A. 1 years B. $1 \frac{1}{2}$ years C. 2 years D. 3 yearsAnswer: Option C
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Solution(By Apex Team)
According to the question,
Average age of a family of 5 members 3 years ago
= 17 years sum of ages of a family members
= 5 × 17
= 85 years
A baby having been born the average age of the family is same today.
∴ Sum of age of a family of 6 members
= 17 × 6
= 102 years
∴ Sum of age of a family of 5 members at present
$\begin{array}{l}\text{= 85 + 5 × 3}\\
\text{= 85 + 15}\\
\text{= 100 years}\\
\text{∴ Age of child}\\
\text{= 102 – 100 = 2 years}\end{array}$