Question

The average monthly income of a person in a certain family of 5 members is rs 1000. What will be monthly average income of a one person in same family, the incme of one person increased by rs 12000 per year

Answer 1

Hi ,

we know that mean formula ;
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Mean = (sum of the observations ) / ( number of observations ) ------( 1 )
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According to the problem ,

sum of the incomes of the 5 members in the family = Rs y

given ,

Average salary of the family = Rs 1000

⇒ y / 5 = 1000

        y = 5000 ----- ( 2 ) 

if one member annual income increase Rupees  12000 then

increase his  monthly average income = Rs 1000

now ,

sum of 5 members income now = y + 1000 

                                                   = 5000 + 1000 = Rs 6000       [ from ( 2 ) ]

New average income = 6000/ 5 = 1200   [ from ( 1  ) ]

Required average salary of the family = Rs 1200

I hope this helps you.

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Answer 2

Given:

"Average income" of 5 persons in a family is Rs. 1000

The "income" of a person increase Rs. 12000 per year

To find:

New average income of one person

Solution:

$Mean = \frac {\text {sum of the observations}} {\text {number of observations}}$

The sum of the income of five members in a family is Rs Y

The average salary of the 5 members is = Rs. 1000

$\frac {y}{5} = 1000$

y = 5000

If monthly income of 1 person increase by Rs. 12000 every year

Then the average income of the family increases by $= \frac {12000} {12}$

= Rs. 1000

Sum of 5 members income after the increase = y + 1000

= 5000 + 1000 = Rs. 6000

New average income of the family $= \frac {6000} {5} = Rs. 1200$

= Rs. 1200