Question

4. Mean of 10 observations was found to be 20. Later on, it was detected that an observation 15
was misread as 10. The correct mean of the observation is: *​

Answer 1

Answer:

the answer is option A 20.5

Answer 2

$Given \: Number \: of \: observations(n) = 10,\\ mean (\bar{x}) = 20 , \\Wrong \: observation (w) = 10 , \\Right \: observation (r) = 15$

$\red{ New \: mean } \green{ = \frac{ \bar{x} \times n - w + r }{n }}$

$= \frac{ 20\times 10 - 10 + 15 }{10} \\= \frac{200 + 5}{10} \\= \frac{205}{10} \\= 20.5$

Therefore .,

$\red{ New \: mean }\green { = 20.5}$

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