The mean age of $25$ teachers in a school is $40$ years. $A$ teacher retires at the age of $60$ years and a new teacher is appointed in his place. If the mean age of the teachers in this school now is $39$ years,then the age (in years) of the newly appointed teacher is..........
- A$40$
- B$35$
- C$48$
- D$56$
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Similar Questions
The mean and variance of $7$ observations are $8$ and $16$ respectively. If the first five observations are $2, 4, 10, 12, 14$,then the absolute difference of the remaining two observations is
Let the mean and variance of four numbers $3, 7, x$ and $y$ $(x > y)$ be $5$ and $10$ respectively. Then the mean of four numbers $3+2x, 7+2y, x+y$ and $x-y$ is ..... .
DifficultJEE MAIN 2021
View SolutionLet the mean of the data be $5$. $X$ $1$ $3$ $5$ $7$ $9$ $f$ $4$ $24$ $28$ $\alpha$ $8$
If $m$ and $\sigma^2$ are respectively the mean deviation about the mean and the variance of the data,then $\frac{3 \alpha}{m+\sigma^2}$ is equal to $..........$.
| $X$ | $1$ | $3$ | $5$ | $7$ | $9$ |
| $f$ | $4$ | $24$ | $28$ | $\alpha$ | $8$ |
DifficultJEE MAIN 2023
View SolutionIf the coefficient of variation is $ 60 $ and the standard deviation is $ 24 $,then the arithmetic mean is:
DifficultKCET 2017
View SolutionTwo sets,each of $20$ observations,have the same standard deviation $5$. The first set has a mean $17$ and the second a mean $22$. Determine the standard deviation of the set obtained by combining the given two sets.
Medium
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