Find the standard deviation for the following data:
${x_i}$
$3$
$8$
$13$
$18$
$25$
${f_i}$
$7$
$10$
$15$
$10$
$6$
Find the standard deviation for the following data:
| ${x_i}$ | $3$ | $8$ | $13$ | $18$ | $25$ |
| ${f_i}$ | $7$ | $10$ | $15$ | $10$ | $6$ |
Let us form the following Table :
| ${x_i}$ | ${f_i}$ | ${f_i}{x_i}$ | ${x_i}^2$ | ${f_i}{x_i}^2$ |
| $3$ | $7$ | $21$ | $9$ | $63$ |
| $8$ | $10$ | $80$ | $64$ | $640$ |
| $13$ | $15$ | $195$ | $169$ | $2535$ |
| $18$ | $10$ | $180$ | $324$ | $3240$ |
| $23$ | $6$ | $138$ | $529$ | $3174$ |
| $48$ | $614$ | $9652$ |
Now, by formula $(3),$ we have
$\sigma = \frac{1}{N}\sqrt {N\sum {{f_i}x_i^2 - {{\left( {\sum {{f_i}{x_i}} } \right)}^2}} } $
$=\frac{1}{48} \sqrt{48 \times 9652-(614)^{2}}$
$=\frac{1}{48} \sqrt{463296-376996}$
$=\frac{1}{48} \times 293.77=6.12$
Therefore, Standard deviation $(c)=6.12$
Similar Questions
Let $a_1, a_2, \ldots . a_{10}$ be $10$ observations such that $\sum_{\mathrm{k}=1}^{10} \mathrm{a}_{\mathrm{k}}=50$ and $\sum_{\forall \mathrm{k}<\mathrm{j}} \mathrm{a}_{\mathrm{k}} \cdot \mathrm{a}_{\mathrm{j}}=1100$. Then the standard deviation of $a_1, a_2, \ldots, a_{10}$ is equal to :
Let $a_1, a_2, \ldots . a_{10}$ be $10$ observations such that $\sum_{\mathrm{k}=1}^{10} \mathrm{a}_{\mathrm{k}}=50$ and $\sum_{\forall \mathrm{k}<\mathrm{j}} \mathrm{a}_{\mathrm{k}} \cdot \mathrm{a}_{\mathrm{j}}=1100$. Then the standard deviation of $a_1, a_2, \ldots, a_{10}$ is equal to :
- [JEE MAIN 2024]
Determine mean and standard deviation of first n terms of an $A.P.$ whose first term is a and common difference is d.
Determine mean and standard deviation of first n terms of an $A.P.$ whose first term is a and common difference is d.
Suppose values taken by a variable $x$ are such that $a \le {x_i} \le b$, where ${x_i}$ denotes the value of $x$ in the $i^{th}$ case for $i = 1, 2, ...n.$ Then..
Suppose values taken by a variable $x$ are such that $a \le {x_i} \le b$, where ${x_i}$ denotes the value of $x$ in the $i^{th}$ case for $i = 1, 2, ...n.$ Then..
Calculate the mean, variance and standard deviation for the following distribution:
Class
$30-40$
$40-50$
$50-60$
$60-70$
$70-80$
$80-90$
$90-100$
$f_i$
$3$
$7$
$12$
$15$
$8$
$3$
$2$
Calculate the mean, variance and standard deviation for the following distribution:
| Class | $30-40$ | $40-50$ | $50-60$ | $60-70$ | $70-80$ | $80-90$ | $90-100$ |
| $f_i$ | $3$ | $7$ | $12$ | $15$ | $8$ | $3$ | $2$ |
The variance of $20$ observation is $5$ . If each observation is multiplied by $2$ , then the new variance of the resulting observations, is
The variance of $20$ observation is $5$ . If each observation is multiplied by $2$ , then the new variance of the resulting observations, is