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  • The mean of 25 observations was found to be 78.4. But later on, it was found that 96 was misread as 69. The correct

The mean of 25 observations was found to be 78.4. But later on, it was found that 96 was misread as 69. The correct mean is

Option: 1

79.48


Option: 2

76.54


Option: 3

81.32


Option: 4

78.4


Answers (1)

best_answer

We know that the mean is given by

\bar{x}=\frac{\sum x}{n}\: or \: \sum x=n\bar{x}\\*\\* \text{Here} \: \bar{x}=78.4,n=25

\therefore \sum x=25 \times 78.4=1960

But this \sum x is incorrect as 96 was misread as 69

Correct \sum x= 1960 – 69 + 96 = 1987

Correct mean  = 1987/25 = 79.48

Posted by

rishi.raj

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