The average of $X_{1}, X_{2}$ and $X_{3}$ is $14$. Twice the sum of $X_{2}$ and $X_{3}$ is $30$. What is the value of $X_{1}$?

The average of the first $9$ integral multiples of $3$ is

$A$ man spends on an average $Rs. 269.47$ for the first $7$ months and $Rs. 281.05$ for the next $5$ months. Find out his monthly salary if he saved $Rs. 308.46$ during the year. (in $Rs.$)

The average weight of $100$ students is $32\, kg$. The average weight of the first $49$ students is $30\, kg$ and that of the last $50$ students is $34\, kg$. What is the weight (in $kg$) of the $50^{th}$ student?

Average of $a, b$ and $c$ is $11$; average of $c, d$ and $e$ is $17$; average of $e$ and $f$ is $22$ and average of $e$ and $c$ is $17$. Find out the average of $a, b, c, d, e$ and $f$?

The average weight of $3$ persons is $65 \, kg$. If a fourth person having a weight of $45 \, kg$ joins the group,what is the average weight of the group? (in $kg$)