Question

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

Answer 1

Mean of given observations =`"sun of given observations"/" total number of observations"`
Mean of 25 observations = 27
∴ Sum of 25 observations = 27 × 25 = 675
If 7 is subtracted from every number, then the sum = 675 – (25 × 7)
                                                                                 = 675 – 175
                                                                                 = 500
Then, new mean =`500/25` = 20
Thus, the new mean will be 20.