Answer :

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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