Question

mean of 20 observation is 17. if 20 is subtracted from the sum of observation, then determine the sum remaining.

Answer 1

mean =20
no. of observations = 17
sum = 340
340-25=315

Answer 2

Let the sum of observations be x
No.of observations = 20
Mean = 17
⇒ Sum of observations/No.of observations = 17
⇒ x/20 = 17
⇒ x = 17×20
∴ x = 140
∴ The sum of the observations is 140
If 20 is subtracted from the sum of observations then the remaining 
sum = 140 - 20 = 120