The mean age of $25$ teachers in a school is $40 \text{ years}$. $A$ teacher retires at the age of $60 \text{ years}$ and a new teacher is appointed in his place. If now the mean age of the teachers in this school is $39 \text{ years}$,then the age (in years) of the newly appointed teacher is
- A$25$
- B$30$
- C$35$
- D$40$
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Which of the following is not a measure of central tendency?
Easy
View SolutionThe mean and the standard deviation of $10$ observations are $20$ and $2$ respectively. Each of these $10$ observations is multiplied by $p$ and then reduced by $q$,where $p \neq 0$ and $q \neq 0$. If the new mean and new standard deviation (s.d.) become half of the original values,then $q$ is equal to
DifficultJEE MAIN 2020
View SolutionIf the mean of two samples of sizes $20$ and $30$ are $25$ and $10$ respectively,and their variances are $9$ and $16$ respectively,then their combined variance is:
Consider the given data with frequency distribution:
$x_{i} = \{3, 8, 11, 10, 5, 4\}$
$f_{i} = \{5, 2, 3, 2, 4, 4\}$
Match each entry in List-$I$ to the correct entries in List-$II$.
List-$I$ List-$II$ $(P)$ The mean of the above data is $(1) 2.5$ $(Q)$ The median of the above data is $(2) 5$ $(R)$ The mean deviation about the mean of the above data is $(3) 6$ $(S)$ The mean deviation about the median of the above data is $(4) 2.7$ $(5) 2.4$
The correct option is :
$x_{i} = \{3, 8, 11, 10, 5, 4\}$
$f_{i} = \{5, 2, 3, 2, 4, 4\}$
Match each entry in List-$I$ to the correct entries in List-$II$.
| List-$I$ | List-$II$ |
| $(P)$ The mean of the above data is | $(1) 2.5$ |
| $(Q)$ The median of the above data is | $(2) 5$ |
| $(R)$ The mean deviation about the mean of the above data is | $(3) 6$ |
| $(S)$ The mean deviation about the median of the above data is | $(4) 2.7$ |
| $(5) 2.4$ |
The correct option is :
Let the mean and variance of the frequency distribution be $6$ and $6.8$ respectively.
$x$ $2$ $6$ $8$ $9$ $f$ $4$ $4$ $\alpha$ $\beta$
If $x_{3}$ is changed from $8$ to $7$,then the mean for the new data will be:
| $x$ | $2$ | $6$ | $8$ | $9$ |
| $f$ | $4$ | $4$ | $\alpha$ | $\beta$ |
If $x_{3}$ is changed from $8$ to $7$,then the mean for the new data will be:
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