Question

The mean of eight numbers is 40. If one number
is excluded, their mean becomes 30. The ex-
cluded number is
0 30
130
0 110
0 138

Answer 1

pls make me brainlist brother...........

Answer 2

Therefore the value of the excluded term is 110. ( Option-c )

Given:

The mean of 8 numbers = 40

If one number is excluded, then their mean becomes 30.

To Find:

The excluded number.

Solution:

The given question can be solved as shown below.

Let the 8 numbers be x₁, x₂, ...., x₈

Mean = ( Sum of terms ) / ( Number of terms )

Given that,

The mean of 8 numbers = 40

⇒ ( x₁ + x₂ + .... + x₈ )/8 = 40

⇒ Then the sum of 8 terms = ( x₁ + x₂ + .... + x₈ ) = 8×40 = 320     (i.)

If one number is excluded, then their mean becomes 30.

Let us assume that, x₈ is excluded.

⇒ Then new mean = ( x₁ + x₂ + .... + x₇ )/7 = 30

⇒ Then the sum of 7 terms = ( x₁ + x₂ + .... + x₇ ) = 7×30 = 210     (ii.)

Subtracting equation-(ii.) from the equation-(i.),

⇒ ( x₁ + x₂ + .... + x₈ ) - ( x₁ + x₂ + .... + x₇ ) = 320 - 210

⇒ x₈ = 110

Therefore the value of the excluded term is 110.

#SPJ2