Suppose mean of a series of 5 items is 30. Four values are, 10,15,30 and 35 respectively. Find the missing (5th) value of the series.

Explanation

Assume 5th value as `X_(5)`.
`barX=(X_(1)+X_(2)+X_(3)+X_(4)+X_(5))/N`
`"Given: "X_(1)=10,X_(2)=15,X_(3)=30,X_(4)=35,X_(5)=?`
`barX=30,N=5`
`30=(10+15+30+35+X_(5))/5=(90+X_(5))/5`
`:." "30xx5=90+X_(5)`
`Or,150=90+X_(5)`
`:." "X_(5)=150-90`
`=60`
Thus, Value of the 5th item = 60.