Question

the mean of 25 obeservation is 36 out of these obeservation if the mean of first of 13 obeservation is 32 and that of the last 13 obeservation is 40.the 13th obeservation

Answer 1

mean of 25 observations = 36

⇒sum of observations = 36 × 25 = 900

⇒sum of observations = 36 × 25 = 900

⇒sum of first 13 observations = 32 × 13 = 416

⇒mean of last 13 observations = 40

⇒sum of last 13 observations = 40 × 13 = 520

∴13th observation =(sum of 1st three observation+sum of last 13 observations)-sum of all observation

==== (416 + 520) – 900

==== 936 – 900

==== 36 is the required answer