Statistics

For a data consisting of 15 observations $x_i$, $i=1,2,3, \ldots, 15$ the following results are obtained : $\sum_{i=1}^{15} x_i=170 ; \sum_{i=1}^{15} x_i^2=2830$. If one of the observation namely 20 was found wrong and…

The arithmetic mean of the observations $10,8,5, a, b$ is 6 and their variance is 6.8 , then $a b$ is equal to

The coefficient of variation of \(9,3,11,5,7\), is

A number equal to $2$ times the mean and with a frequency equal to $k$ is inserted in a data having$n$ observations. If the new mean is $\frac{4}{3}$ times the old mean, then the value of$\frac{k}{n}$ is

Let ${X}_{n}$ denote the mean of first $n$ natural numbers, then the mean of ${X}_{1}, {X}_{2}, ..., {X}_{100}$ is

The mean of $n$ items is $\vec{x}\cdot$ If the first item is increased by $n,$ second by $n-1$ and so on and last by $1,$ then the new mean is

For two data sets each of size 5 , the variance are given to be 4 and 5 and the corresponding means are given to be 2 and 4 respectively. The variance of the combined data set is

The mean and variance of the observations $\mathrm{x}_1, \mathrm{x}_2, \mathrm{x}_3, \ldots, \mathrm{x}_{15}$ are respectively 2 and 4. If the mean and variance of the observations $y_1, y_2, \ldots, y_{10}$ are…

If the standard deviation of data is 12 and mean is 72 , then coefficient of variation is

If $2$ data sets having $10$ and $20$ observations have coefficients of variation $50$ and $60$ respectively and arithmetic means $30$ and $25$ respectively, then the combined variance of those $30$ observations is

A random variable $\mathrm{X}$ takes the values $0,1,2$. Its mean is $1 \cdot 2 .$ If $\mathrm{P}(\mathrm{X}=0)=0.3$, then $\mathrm{P}(\mathrm{X}=1)=$

For a group of $50$ male workers, the mean and the standard deviation of their daily wages are $\text{Rs}\cdot \text{}630$ and $\text{Rs}\cdot \text{}90$ respectively and for a group of $40$ female workers these are…