Question

6. The mean of nine observations was found to be 40. Later on, it was discovered that an observation 81 was misread 18. Find the correct mean of the observations.

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Answer 1

Answer:

mean of nine observation is 40

total of nine observation is 9×40=360

one observation counting 81 is wrong

so total of 8 observation is 360-81=279

actually it is 18

so actual total of 9 observation is 279+18=297

correct mean of nine observation is 297/9=33

correct mean of the observations is 33

Answer 2

$\red{\textbf{Answer :- 47}}$

Step-by-step explanation:

$\red{\textbf{Given:-}}$

$\textsf{Incorrect mean of 9 observations =40}$

$\textsf{Incorrect sum of observations =40×9}$

$\textsf{= 360}$

$\textsf{Since, 81 is misread as 18.}$

$\red{\textbf{To find :-}}$

$\textsf{the correct mean of the observations. }$

$\textsf{So, correct sum of observations}$

$\textsf{=360−18+81}$

$\textsf{= 423}$

∴$\textsf{The correct mean =}$

$\Large \frac{423}{9} \small = 47$

$\Large\textsf{so, the correct mean =}$

$\LARGE\textsf{47}$