Average age of 15 students of a class is 15, year. Oute of these, average age of 5 students is 14 ,y

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The average age of $15$ students of a class is $15\, year.$ Oute of these, the average age of $5$ students is $14 \,year$ and that of the other $9$ students is $16\, year.$ The age of the $15^{th}$ students is? (in $year$)

A

$11$

B

$15$

C

$15 \frac{2}{7}$

D

$14$

Solution

Age of $15^{\text {th }}$ student $=15 \times 15-(5 \times 14)-(9 \times 16)$

$\quad=225-70-144=11$ year

Standard 13

Quantitative Aptitude

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