Descriptive Sta...

The variance of numbers $$x_1, x_2, x_3,..... x_n$$ is V. Consider the following statements : 
1. If every $$x_1$$, is increased by 2, the variance of the new set of numbers is V.
2. If the numbers $$x_1$$ is squared, the variance of the new set is $$V^2$$.
Which of the following statements is/are correct ?

Calculate the standard deviation of the first $$13$$ natural numbers.

The variance of first '$$n$$' natural number is

Calculate the standard deviation of the following data.
$$10, 20, 15, 8, 3, 4$$

What is the ratio of the total sales of branch B2 for both years to the total sales of branch B4 for both years?

If the mean of the numbers $$a,b,8,5,10$$ is $$6$$ and their variance is $$68$$, then $$ab$$ is equal to

If the median of the data 6,7,x-2,x,18,21 written in ascending order is 16, then the variance of that data is 

For the data set below, which value is in the 75th percentile?
$$1, 3, 3, 4, 6, 7, 7, 7, 8, 9, 9, 10, 12, 15, 16, 17$$

What is the total expenditure (Rs. in lakhs) of the company during the period January to July in the year 2003?

If the variance of $$1, 2, 3, 4, 5, ..., x$$ is $$10$$, then the value of $$x$$ is