If the mean deviation about the mean of the numbers $1,2,3, \ldots ., n$, where $n$ is odd, is $\frac{5(n+1)}{n}$, then $n$ is equal to
If the mean deviation about the mean of the numbers $1,2,3, \ldots ., n$, where $n$ is odd, is $\frac{5(n+1)}{n}$, then $n$ is equal to
- [JEE MAIN 2022]
- A
$20$
- B
$25$
- C
$23$
- D
$21$
Similar Questions
The mean and standard deviation of $15$ observations are found to be $8$ and $3$ respectively. On rechecking it was found that, in the observations, $20$ was misread as $5$ . Then, the correct variance is equal to......
The mean and standard deviation of $15$ observations are found to be $8$ and $3$ respectively. On rechecking it was found that, in the observations, $20$ was misread as $5$ . Then, the correct variance is equal to......
- [JEE MAIN 2022]
Consider the statistics of two sets of observations as follows :
Size
Mean
Variance
Observation $I$
$10$
$2$
$2$
Observation $II$
$n$
$3$
$1$
If the variance of the combined set of these two observations is $\frac{17}{9},$ then the value of $n$ is equal to ..... .
Consider the statistics of two sets of observations as follows :
| Size | Mean | Variance | |
| Observation $I$ | $10$ | $2$ | $2$ |
| Observation $II$ | $n$ | $3$ | $1$ |
If the variance of the combined set of these two observations is $\frac{17}{9},$ then the value of $n$ is equal to ..... .
- [JEE MAIN 2021]
Calculate mean, variance and standard deviation for the following distribution.
Classes
$30-40$
$40-50$
$50-60$
$60-70$
$70-80$
$80-90$
$90-100$
${f_i}$
$3$
$7$
$12$
$15$
$8$
$3$
$2$
Calculate mean, variance and standard deviation for the following distribution.
| Classes | $30-40$ | $40-50$ | $50-60$ | $60-70$ | $70-80$ | $80-90$ | $90-100$ |
| ${f_i}$ | $3$ | $7$ | $12$ | $15$ | $8$ | $3$ | $2$ |
In any discrete series (when all values are not same) the relationship between $M.D.$ about mean and $S.D.$ is
In any discrete series (when all values are not same) the relationship between $M.D.$ about mean and $S.D.$ is
Let in a series of $2 n$ observations, half of them are equal to $a$ and remaining half are equal to $-a.$ Also by adding a constant $b$ in each of these observations, the mean and standard deviation of new set become $5$ and $20 ,$ respectively. Then the value of $a^{2}+b^{2}$ is equal to ....... .
Let in a series of $2 n$ observations, half of them are equal to $a$ and remaining half are equal to $-a.$ Also by adding a constant $b$ in each of these observations, the mean and standard deviation of new set become $5$ and $20 ,$ respectively. Then the value of $a^{2}+b^{2}$ is equal to ....... .
- [JEE MAIN 2021]