Find the average of squares of consecutive even numbers from $1$ to $25$.

A train covers the first $160 \mathrm{km}$ at a speed of $120 \mathrm{km}/\mathrm{h}$, another $160 \mathrm{km}$ at $140 \mathrm{km}/\mathrm{h}$ and the last $160 \mathrm{km}$ at $80 \mathrm{km}/\mathrm{h}$. Find the average speed (in $\mathrm{km}/\mathrm{h}$) of the train for the entire journey.

Find the average of the following set of scores.

$142,93,102,206,115,98$

In a cricket team, the average age of $11$ players and the coach is$18$ years. If the age of the coach is not considered, then the average decreases by $1$ year. Find out the age of the coach.

The average of marks secured by $35$ students is $72$. If the marks secured by one student was written as $36$ instead of $86$, then find the correct average.

The average weight of $8$ persons are increased by $1.5 \mathrm{kg}$. If a person weighing $65 \mathrm{kg}$ is replaced by a new person, what could be the weight of new person?