The mean and variance of 5 observations are 5 and 8 respectively. If 3 observations are 1, 3, 5, then the sum of cubes of the remaining two observations is :
Let the mean and the standard deviation of the observation $2,3,3,3,4,5,7,a,b$ be $4$ and $\sqrt{2}$ respectively. Then the mean deviation about the mode of these observations is:
If $\sum\limits_{i = 1}^n {\left( {{x_i} - a} \right)} = n$ and $\sum\limits_{i = 1}^n {{{\left( {{x_i} - a} \right)}^2}} = na$(n, a > 1) then the standard deviation of n observations x1, x2, ..., xn is :
If mean and standard deviation of 5 observations $x_1,x_2,x_3,x_4,x_5$ are $10$ and $3$ respectively, then the variance of 6 observations $x_1,x_2,\ldots,x_5$ and $-50$ is equal to :
All the students of a class performed poorly in Mathematics. The teacher
decided to give grace marks of $10$ to each of the students. Which of the
following statistical measures will not change even after the grace marks were
given?
The outcome of each of 30 items was observed; 10 items gave an outcome $\dfrac{1}{2}-d$ each, 10 items gave outcome $\dfrac{1}{2}$ each and the remaining 10 items gave outcome $\dfrac{1}{2}+d$ each. If the variance of this outcome data is $\dfrac{4}{3}$ then $|d|$ equals :
The mean and variance of a set of $15$ numbers are $12$ and $14$ respectively.
The mean and variance of another set of $15$ numbers are $14$ and $\sigma^{2}$ respectively.
If the variance of all the $30$ numbers in the two sets is $13$, then $\sigma^{2}$ is equal to:
The mean and standard deviation of $100$ observations are $40$ and $5.1$, respectively. By mistake one observation is taken as $50$ instead of $40$. If the correct mean and the correct standard deviation are $\mu$ and $\sigma$ respectively, then $10(\mu+\sigma)$ is equal to
The mean of set of $30$ observations is $75$. If each observation is multiplied by a non-zero number $\lambda$ and then each of them is decreased by $25$, their mean remains the same. Then $\lambda$ is equal to :
The mean and standard deviation of 20 observations were calculated as 10 and 2.5 respectively. It was found that by mistake one data value was taken as 25 instead of 35. if $\alpha$ and $\sqrt \beta $ are the mean and standard deviation respectively for correct data, then ($\alpha$, $\beta$) is :
For a statistical data $x_1, x_2, \ldots, x_{10}$ of $10$ values, a student obtained the mean as $5.5$ and $\sum_{i=1}^{10} x_i^2 = 371$. He later found that he had noted two values in the data incorrectly as $4$ and $5$, instead of the correct values $6$ and $8$, respectively. The variance of the corrected data is
The mean and variance of $12$ observations are $\dfrac{9}{2}$ and $4$ respectively. Later, it was observed that two observations were considered as $9$ and $10$ instead of $7$ and $14$ respectively. If the correct variance is $\dfrac{m}{n}$, where $m$ and $n$ are coprime, then $m+n$ is equal to:
If $\displaystyle \sum_{i=1}^{9}(x_i-5)=9$ and $\displaystyle \sum_{i=1}^{9}(x_i-5)^{2}=45$, then the standard deviation of the $9$ items $x_1,x_2,\ldots,x_9$ is :
The mean and standard deviation of $20$ observations are found to be $10$ and $2$, respectively. On rechecking, one observation recorded as $8$ was actually $12$. The corrected standard deviation is:
The mean and the variance of five observations are $4$ and $5.20$, respectively. If three of the observations are $3, 4$ and $4$, then the absolute value of the difference of the other two observations is:
The mean and the standard deviation (s.d.) of five observations are $9$ and $0$, respectively. If one of the observations is changed such that the mean of the new set of five observations becomes $10$, then their s.d. is:
Let $\mu$ be the mean and $\sigma$ be the standard deviation of the distribution
where $\displaystyle \sum f_i = 62$.
If $[x]$ denotes the greatest integer $\le x$, then $[\mu^2 + \sigma^2]$ is equal to:
If the mean and variance of five observations are $\dfrac{24}{5}$ and
$\dfrac{104}{25}$ respectively, and the mean of the first four observations is
$\dfrac{7}{2}$, then the variance of the first four observations is equal to:
The mean of the numbers a, b, 8, 5, 10 is 6 and their variance is 6.8. If M is the mean deviation of the numbers about the mean, then 25 M is equal to :
Let $X = \{x \in \mathbb{N} : 1 \leq x \leq 17\}$ and
$Y = \{ax + b : x \in X,\; a \in \mathbb{R},\; b \in \mathbb{R},\; a > 0\}$.
If mean and variance of elements of $Y$ are $17$ and $216$ respectively,
then $a + b$ is equal to :
Consider three observations a, b, and c such that b = a + c. If the standard deviation of a + 2, b + 2, c + 2 is d, then which of the following is true?
Let sets A and B have 5 elements each. Let the mean of the elements in sets A and B be 5 and 8 respectively and the variance of the elements in sets A and B be 12 and 20 respectively. A new set C of 10 elements is formed by subtracting 3 from each element of and adding 2 to each element of . Then the sum of the mean and variance of the elements of is ___________.
The mean and standard deviation of 50 observations are 15 and 2 respectively. It was found that one incorrect observation was taken such that the sum of correct and incorrect observations is 70. If the correct mean is 16, then the correct variance is equal to :
The mean and variance of seven observations are $8$ and $16$, respectively. If five of the observations are $2,4,10,12,14$, then the product of the remaining two observations is:
Let the six numbers $a_{1},a_{2},a_{3},a_{4},a_{5},a_{6}$ be in A.P. and $a_{1}+a_{3}=10$.
If the mean of these six numbers is $\dfrac{19}{2}$ and their variance is $\sigma^{2}$, then $8\sigma^{2}$ is equal to:
For the frequency distribution : Variate (x) : x1 x2 x3 .... x15 Frequency (f) : f1 f2 f3...... f15 where 0 < x1 < x2 < x3 < ... < x15 = 10 and $\sum\limits_{i = 1}^{15} {{f_i}} $ > 0,
the standard deviation cannot be :
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 :
The mean age of 25 teachers in a school is 40 years. A teacher retires at the age of 60 years and a new teacher is appointed in his place. If now the mean age of the teachers in this school is 39 years, then the age (in years) of the newly appointed teacher is :
In an increasing geometric progression of positive terms, the sum of the second and sixth terms is $\dfrac{70}{3}$ and the product of the third and fifth terms is $49$. Then the sum of the $4^{\text{th}},6^{\text{th}}$ and $8^{\text{th}}$ terms is equal to:
A student scores the following marks in five tests: $45,,54,,41,,57,,43$. His score is not known for the sixth test. If the mean score is $48$ in the six tests, then the standard deviation of the marks in six tests is:
The mean and variance of five observations are $\dfrac{24}{5}$ and $\dfrac{194}{25}$ respectively. If the mean of the first four observations is $\dfrac{7}{2}$, then the variance of the first four observations is:
The sum of $100$ observations and the sum of their squares are $400$ and $2475$, respectively.
Later on, three observations, $3,4$ and $5$, were found to be incorrect.
If the incorrect observations are omitted, then the variance of the remaining observations is:
The mean and the median of the following ten numbers in increasing order $10,22,26,29,34,x,42,67,70,y$ are $42$ and $35$ respectively, then $\dfrac{y}{x}$ is equal to:
The mean and standard deviation of 10 observations are 20 and 8 respectively. Later on, it was observed that one observation was recorded as 50 instead of 40. Then the correct variance is :
Let xi (1 $ \le $ i $ \le $ 10) be ten observations of arandom variable X. If $\sum\limits_{i = 1}^{10} {\left( {{x_i} - p} \right)} = 3$ and $\sum\limits_{i = 1}^{10} {{{\left( {{x_i} - p} \right)}^2}} = 9$ where 0 $ \ne $ p $ \in $ R, then the standard deviation of these observations is :
Let the mean and the variance of 5 observations $x_1, x_2, x_3, x_4, x_5$ be $\dfrac{24}{5}$ and $\dfrac{194}{25}$ respectively. If the mean and variance of the first 4 observations are $\dfrac{7}{2}$ and $a$ respectively, then $(4a + x_5)$ is equal to:
The mean and variance of 8 observations are 10 and 13.5, respectively. If 6 of these observations are 5, 7, 10, 12, 14, 15, then the absolute difference of the remaining two observations is :
The mean and variance of 7 observations are 8 and 16 respectively. If two observations are 6 and 8, then the variance of the remaining 5 observations is :
Five students of a class have an average height $150\ \mathrm{cm}$ and variance $18\ \mathrm{cm}^2$. A new student, whose height is $156\ \mathrm{cm}$, joins them. The variance (in $\mathrm{cm}^2$) of the heights of these six students is:
Let $S$ be the set of all values of $a_1$ for which the mean deviation about the mean of $100$ consecutive positive integers $a_1,a_2,a_3,\ldots,a_{100}$ is $25$. Then $S$ is:
A data consists of $n$ observations: $x_1,x_2,\ldots,x_n$. If
$\displaystyle \sum_{i=1}^{n}(x_i+1)^2=9n$ and $\displaystyle \sum_{i=1}^{n}(x_i-1)^2=5n$,
then the standard deviation of this data is:
The mean of $5$ observations is $5$ and their variance is $124$.
If three of the observations are $1, 2$ and $6$, then the mean deviation from the mean of the data is:
The mean and variance of 7 observations are 8 and 16, respectively. If five observations are 2, 4, 10, 12, 14, then the absolute difference of the remaining two observations is :
If both the mean and the standard deviation of $50$ observations $x_{1},x_{2},\ldots,x_{50}$ are equal to $16$, then the mean of $(x_{1}-4)^{2},(x_{2}-4)^{2},\ldots,(x_{50}-4)^{2}$ is:
Consider $10$ observations $x_{1},x_{2},\ldots,x_{10}$ such that
$\displaystyle \sum_{i=1}^{10}(x_{i}-\alpha)=2$ and $\displaystyle \sum_{i=1}^{10}(x_{i}-\beta)^{2}=40$,
where $\alpha,\beta$ are positive integers.
Let the mean and the variance of the observations be $\dfrac{6}{5}$ and $\dfrac{84}{25}$ respectively.
Then $\dfrac{\beta}{\alpha}$ is equal to:
Let the mean and variance of five observations $x_1=1,\ x_2=3,\ x_3=a,\ x_4=7,\ x_5=b,\ a>b$ be $5$ and $10$ respectively. Then the variance of the observations $n+x_n,\ n=1,2,\ldots,5$ is
The mean of the data set comprising of $16$ observations is $16$. If one of the
observations valued $16$ is deleted and three new observations valued $3,4$
and $5$ are added to the data, then the mean of the resultant data is:
Let the mean and standard deviation of marks of class $A$ of $100$ students be respectively $40$ and $\alpha\ (>\,0)$, and the mean and standard deviation of marks of class $B$ of $n$ students be respectively $55$ and $30-\alpha$. If the mean and variance of the marks of the combined class of $100+n$ students are respectively $50$ and $350$, then the sum of variances of classes $A$ and $B$ is:
Let $\alpha, \beta \in \mathbb{R}$.
Let the mean and the variance of 6 observations $-3,\, 4,\, 7,\,-6,\, \alpha,\, \beta$ be $2$ and $23$, respectively.
The mean deviation about the mean of these 6 observations is:
If the data x1, x2,......., x10 is such that the mean of first four of these is 11, the mean of the remaining six is
16 and the sum of squares of all of these is 2,000 ; then the standard deviation of this data is :
Marks obtained by all the students of class 12 are presented in a frequency distribution with classes of equal width. The median of this grouped data is $14$ with median class interval $12$–$18$ and median class frequency $12$. If the number of students whose marks are less than $12$ is $18$, then the total number of students is:
If the center and radius of the circle $\left|\dfrac{z-2}{z-3}\right|=2$ are respectively $(\alpha,\beta)$ and $\gamma$, then $3(\alpha+\beta+\gamma)$ is equal to: