Q5 of 37 Page 14

If the mean of 25 observations is 27 and each observation is decreased by 7, what will be the new mean?[CBSE 2014]

Mean of the observation is given by –


Total number of observations = 25


Mean of 25 observation = 27 (Given)


We get



⇒ Sum of 25 observations = 27 × 25 = 675


If each observation is decreased by 7, the Sum gets affected.


New Sum = 675 – (25 × 7) = 675 – 175 = 500



Thus, new mean = 20

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