Statistics practice · Mixed difficulty

The coefficient of variation of two series are $58 \%$ and $69 \%$. If their standard deviations are 21.2 and 15.6 , then their A.Ms are

Ravi obtained 70 and 75 marks in first two unit tests. Then, the minimum marks he should get in the third test to have an average of at least 60 marks, are

Mode of the data $3,2,5,2,3,5,6,6,5,3,5,2,5$ is-

The co-efficient of rank correlation of marks obtained by 10 students in Statistics and Accountancy was found to be 0.2 . It was later discovered that the difference in ranks in the two subjects obtained by one of the students was wrongly taken as 9 instead of 7 . The correct value of co-efficient of rank correlation is

Let the mean and the variance of 5 observations $x_1$, $x_2, x_3, x_4, x_5$ be $\frac{24}{5}$ and $\frac{194}{25}$ respectively. If the mean and variance of the first 4 observation are $\frac{7}{2}$ and a respectively, then $\left(4 a+x_5\right)$ is equal to

Given the following results for the height $(x)$ and weight (y) in appropriate units of 1000 students: $\bar{x}=68$, $\bar{y}=150, \sigma_x=2.5, \sigma_y=20, r=0.60$.
The height of a student A who weights 200 units is

The weighted mean of first $n$ natural numbers whose weights are equal to the squares of corresponding numbers is

The mean of 5 observations is 3 and variance is 2. If three of the five observations are 1, 3, 5 the other two are

The mean income of a group of workers is $X$ and that of another group is $Y$. If the number of workers in the second group is 10 times the number of workers in the first group, then mean income of combined group is

If $x$ and $y$ are independent variables, then two lines of regression are

The mean of $1,2,6$, a, b is 4 and their variance is 5.2 then $(\mathrm{a}, \mathrm{b})$

If variance of $X, Y, X-Y$ are respectively $\sigma_x^2, \sigma_y^2, \sigma_{x-y}^2$, then the coefficient of correlation $r$ between two variables $X$ and $Y$ is given by

If the variables with values 10, 20, 30, 40 have frequencies $x, x+2, x-2, x+4$ and the mean is 2.7 then the value of $x$ is

If the mean and variance of six observations 7, 10, 11, 15, $a$, $b$ are 10 and $\frac{{20}}{3}$ respectively, then the value of $\left| {a - b} \right|$ is equal to

If in a frequency distribution, the mean and median are 25 and 26 , then its mode is approximately.

A.M. of $C_0, 2 C_1, 3 C_2, \ldots,(n+1) C_n$, where $(1+x)^n=C_0+C_1 x+$ $C_2 x^2+\cdots+C_n x^n$ is equal to

The number of runs scored by 11 players of a cricket team of school are $5,19,42$, $11,50,30,21,0,52,36,27$. The median is-

The values of mean, median and mode coincide, then the distribution is

If a variate $X$ is expressed as a linear function of two variates ${\cal U}\;and\;\;V$ the form $X = a\;{\cal U} + b\;V,$ then mean $\bar X\;of\,X$ is

Let the sum of the first three terms of an A. P, be 39 and the sum of its last four terms be 178 . If the first term of this A.P. is 10 , then the median of the A.P. is :

The arithmetic mean of $a, a+d, a+2 d, \ldots, a+2 n d$ is

If $\sum\limits_{{i=1}}^{18}\left(x_i-8\right)=9$ and $\sum\limits_{{i=1}}^{18}\left(x_i-8\right)^2=45$ then the standard deviatioin of $x_1, x_2 \ldots \ldots x_{18}$ is

The mean and variance of the marks obtained by the students in a test are 10 and 4 respectively. Later, the marks of one of the students is increased from 8 to 12. If the new mean of the marks is 10.2, then their new variance is equal to :

If the values of regression coefficients are -0.33 and -1.33, then the value of coefficients of correlation between the two variables, is

The weighted mean of the first $n$ natural numbers if their weights are the same as the numbers, is

If the mean and variance of the following data: 6, 10, 7, 13, a, 12, b, 12 are 9 and $\frac{{37}}{4}$ respectively, then ${(a - b)^2}$ is equal to

The sum of the four arithmetic means between 4 and 40 is

The sum of square of deviations for 10 observations taken from mean 50 is 250 . The coefficients of variation is

The geometric mean of numbers $7,7^2, 7^3, \ldots ., 7^n$ is :

The mean of 21 observations (all DIFFERENT) IS 40 . If each observations greater than the median are increases 21 then mean of observations will become