Q1 of 48 Page 126

Mean of 100 observations is 40. The 9th observation is 30. If this is replaced by70 keeping all other observations same, find the new mean.

We know that



⇒ Sum of observations = Mean × Total number of observations


⇒ Sum of 100 observations = 40×100 = 4000


For new mean, we will subtract 30 and add 70 to the sum.


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