Question

average of four number is 30. if average of first three number is 85. then find the fourth term.

Answer 1

Mean of four numbers=30
Let sum of all observations be=m and n
Mean=Sum of all observations/No. of observations
30=m/4
m=30*4=120


Mean of first three numbers=85
Mean=n/3
85*3=n
n=255

Fourth term=255-120=135