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Question
Mean of 100 observations is 40. The 9th observation is 30. If this is replaced by 70 keeping all other observations same, find the new mean.
Options
40.6
40.4
40.3
40.7
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Solution
40.4
Explanation:
We have,
Mean of 100 observations is 40.
Total sum of observations = 100 × 40 = 4000
If the 9th observation is 30 and is replaced by 70 keeping all other observations same.
New, total sum of observations = 4000 - 30 + 70 = 4040
So, the new mean = `4040/100` = 40.4
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