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Question
The mean of 5 observations is 50. One of the observations was removed from the data, hence the mean became 45. Find the observation which was removed.
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Solution
∴ Sum of observations = Mean × Total number of observations
⇒ sum of 5 observations = 50 × 5 = 250
Total no of observations when One of the observations was removed from the data = 4
⇒ sum of 4 observations = 45 × 4 = 180
So, the observation which was removed = sum of 5 observations − sum of 4 observations
250 − 180
= 70
The observation which was removed is 70.
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