Mean of given observations = \(\cfrac{sum \,of \,given \,observation}{total \,number \,of \,observation}\)
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.
