Three years ago, average age of a family of 5 members was 17, years. A baby having been born, averag

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4.Average

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Three years ago, the average age of a family of $5$ members was $17\, years.$ A baby having been born, the average age of the family is the same today. The present age of the baby is (in $years$)

A

$1$

B

$1 \frac{1}{2}$

C

$2$

D

$3$

Solution

Average of age of family of $5$ members $(3$ years ago) $=17$ years

$\therefore$ Present age of family of $6$ members with a new born baby $=17$ year

Let the age of baby be $x$

$\frac{(17+3) \times 5+x}{6}=17$

$\frac{100+x}{6}=17$

$100+x=102$

$x=2$ years

Standard 13

Quantitative Aptitude

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