Question

Mean of 5 subject is 30.if one number excluded their mean became 28 find the excluded number is :
A)28
B)30
C)35
D)38

Answer 1

The number that is excluded is 38.

• The mean of 5 numbers is 30.
• If one number is excluded then the mean obtained is 28.
• Let the number excluded be x.
• Now according to the given condition,

$\frac{Sum \ of \ 4 \ numbers + x}{5}$ = 30  (Mean of 5 numbers is 30)

• According to the second condition,

$\frac{Sum \ of \ 4 \ numbers}{4}$ = 28

Sum of 4 numbers  = 112.

• Now substituting the value of 'sum of 4 numbers' in the above equation, we get

$\frac{112 + x}{5} = 30$

112 + x = 150

x = 38