Calculate the variance if $\Sigma x_i^2 = 18000$ and $\Sigma x_i = 960$,for $60$ observations.
- A$44$
- B$22$
- C$32$
- D$6.63$
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Similar Questions
Find the mean and variance for the following data:
$x_i$ $92$ $93$ $97$ $98$ $102$ $104$ $109$ $f_i$ $3$ $2$ $3$ $2$ $6$ $3$ $3$
| $x_i$ | $92$ | $93$ | $97$ | $98$ | $102$ | $104$ | $109$ |
| $f_i$ | $3$ | $2$ | $3$ | $2$ | $6$ | $3$ | $3$ |
Difficult
View SolutionStudents of two sections $A$ and $B$ of a class show the following results in a test conducted for $100$ marks. Then
Section $A$ Section $B$ Number of students $50$ $60$ Average marks in the test $45$ $45$ Variance of distribution of marks $64$ $81$
| Section $A$ | Section $B$ | |
| Number of students | $50$ | $60$ |
| Average marks in the test | $45$ | $45$ |
| Variance of distribution of marks | $64$ | $81$ |
The variance of the first $n$ natural numbers is
Medium
View SolutionThe mean of $100$ observations is $50$ and their standard deviation is $5$. Then,the sum of squares of all observations is
What is the standard deviation of the following series?
Class $0-10$ $10-20$ $20-30$ $30-40$ Frequency $1$ $3$ $4$ $2$
| Class | $0-10$ | $10-20$ | $20-30$ | $30-40$ |
| Frequency | $1$ | $3$ | $4$ | $2$ |
Medium
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