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BITSAT 2010
Exam
BITSAT
Year
2010
Subject
Mathematics
Chapter
Statistics

BITSAT 2010 · Mathematics · Statistics

Mean of 25 observations was found to be 78.4. But later on it was...

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

Options

  1. A79.24
  2. B79.48
  3. C80.10
  4. DNone of these

Correct answer

B. 79.48

Step-by-step solution

Mean (\barx=∑xnorbar{x}=\frac{\sum x}{n} or(\Sigma x=n \bar{x}) (\Sigmax=\mathrm{x}=25 \times78.4=1960) But this (\Sigma x\mathrm{x} is incorrect as 96 was misread as 69. ∴ correct Σx=1960+(96−69)=1987∴ correct mean =198725=79.48\begin{aligned}& \therefore \text{ correct } \Sigma \mathrm{x}=1960+(96-69)=1987 \\ & \therefore \text{ correct mean }=\frac{1987}{25}=79.48 \end{aligned})$
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