Find the mean and variance for the data $6,7,10,12,13,4,8,12$
$6,7,10,12,13,4,8,12$
Mean, $\bar x = \frac{{\sum\limits_{i = 1}^8 {{x_i}} }}{n}$
$=\frac{6+7+10+12+13+4+8+12}{8}=\frac{72}{8}=9$
The following table is obtained
${x_i}$ | $\left( {{x_i} - \bar x} \right)$ | ${\left( {{x_i} - \bar x} \right)^2}$ |
$6$ | $-3$ | $9$ |
$7$ | $-2$ | $4$ |
$10$ | $-1$ | $1$ |
$12$ | $3$ | $9$ |
$13$ | $4$ | $16$ |
$4$ | $-5$ | $25$ |
$8$ | $-1$ | $1$ |
$12$ | $3$ | $9$ |
$74$ |
Variance $\left( {{\sigma ^2}} \right) = \frac{1}{n}\sum\limits_{i = 1}^8 {{{\left( {{x_i} - \bar x} \right)}^2} = \frac{1}{8} \times 74} = 9.25$
Find the variance and standard deviation for the following data:
${x_i}$ | $4$ | $8$ | $11$ | $17$ | $20$ | $24$ | $32$ |
${f_i}$ | $3$ | $5$ | $9$ | $5$ | $4$ | $3$ | $1$ |
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:
What is the standard deviation of the following series
class |
0-10 |
10-20 |
20-30 |
30-40 |
Freq |
1 |
3 |
4 |
2 |
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
The mean and standard deviation of $40$ observations are $30$ and $5$ respectively. It was noticed that two of these observations $12$ and $10$ were wrongly recorded. If $\sigma$ is the standard deviation of the data after omitting the two wrong observations from the data, then $38 \sigma^{2}$ is equal to$.........$