Statistics Test...

$$\sum _{ i=1 }^{ 10 }{ { \left( { X }_{ i }-10 \right)  }^{ 2 }=2000 } \sum _{ i=1 }^{ 10 }{ { X }_{ i }-10 } =100$$ then the standard deviation of data set $${X}_{i}$$.

Find the standard deviation of 10 observation 111, 211, 311,.......,1011.

The mean and standard deviation of $$1,2,3,4,5,6$$ are 

Two sets each of $$20$$ observations, have the same standard deviation $$'5'$$. The first set has a mean $$'17'$$ and the second set mean $$'22'$$ then standard deviation of the combining the given two sets is

The mean deviation from mean of the observation $$a,\ a+d,\ a+2d,....,a+2nd$$ is

The standard deviation of a varibale x is$$\sigma $$. The standard devaition of the varibale $$\frac { ax+b }{ c } $$ where a, b, c are constant is _____________________.

The average marks of 10 students in a class is 60 with standard deviation 4 while the average marks of other 10 students is 40 with standard deviation 6. If all the 20 students are taken together, their standard deviation will be

Ina a class of 20 students, each student can score 10 or 0 marks in a certain examination. The maximum possible variance in the marks of the students in the class is

Consider the first $$10$$ positive integers. If we multiply each number by $$-1$$ and then add $$1$$ to each number, the variance of the numbers so obtained is

If the standard deviation of $$x_1,x_2,...,x_n$$ is 3.5 then the standard deviation of $$2x_1-3,2x_2-3,...,2x_n-3$$ is