If the mean of five observations $x, x + 2, x + 4, x + 6$,and $x + 8$ is $11$,what is the mean of the last three observations?

The following data gives the distribution of height of students. The median of the distribution is:

Height (in $cm$)	$160$	$150$	$152$	$161$	$156$	$154$	$155$
No of students	$12$	$8$	$4$	$4$	$3$	$3$	$7$

For a distribution $x_1, x_2, \dots, x_{101}$ such that $x_1 < x_2 < x_3 < \dots < x_{100} < x_{101}$,the mean deviation of this distribution about a number $k$ is minimum. Then $k$ is equal to which of the following?

If the mean of the series $x_1, x_2, ......., x_n$ is $\bar{x}$,then what will be the mean of the series $x_i + 2i, (i = 1, 2, ......., n)$?

The median of $21$ observations is $40$. If each observation greater than the median is increased by $6$,what will be the new median of the observations?

If a man spends an equal amount of money to buy three types of pens at $5$ Rs/pen,$10$ Rs/pen,and $20$ Rs/pen,what is the average cost per pen?