Statistics Test...

If the two observations are $$10$$ and $$0$$, their arithmetic mean is _______.

The average (arithmetic mean) of a set of seven numbers is $$8$$. When an eighth number is added to the set, the average of the eight numbers is still $$8$$. What number was added to the set?

The sum of first $$n$$ natural numbers is given by the expression $$(2n^{2}+3n)$$. The mean of the given numbers is 

In a school marks obtained by $$10$$ students in mathematics test as given below:
$$18, 12, 36, 24,  40, 60, 23, 09, 70, 62$$
Find Range of this data :

The mean of first ten prime numbers is 

The AM of first $$5$$ whole numbers is:

The marks (out of $$10$$) obtained by $$28$$ students in a
Mathematics test is listed below:
$$8, 1, 2, 6, 5, 5, 5, 0, 1, 9, 7, 8, 0, 5, 8, 3, 0, 8, 10, 10, 3, 4,
8, 7, 8, 9, 2, 0
$$
The number of students who
scored marks less than $$4$$ is 

The range of the data $$ 30,61,55,56,60,20,26,46,28,56 $$ is 

Some integers are marked on a board. The range of these integers is

The range of the data : $$21,6,17,18,12,8,4,13$$ is