The following table gives the number of children of 150 families in a village
No. of children ($x$):  0  1  2  3  4  5 
No. of families ($f$):  10  21  55  42  15  7 
Find the average number of children per family.
Given:
The number of children of 150 families in a village.
To do:
We have to find the average number of children per family.
Solution:
Let the assumed mean be $A=3$
Number of children ($x_i$)  Number of families ($f_i$)  $d_i = x_i A$ $A =3$  $f_i \times\ d_i$ 
0  10  $3$  $30$ 
1  21  $2$  $42$ 
2  55  $1$  $55$ 
3  $A$  42  0  0 
4  15  1  15 
5  7  2  14 
Total  $\sum{f_i}=150$
  $\sum{f_id_i}=98$

We know that,
Mean $=A+\frac{\sum{f_id_i}}{\sum{f_i}}$
Therefore,
Mean $=3+\frac{98}{150}$
$=30.65$
$=2.35$
The number of children per family is $2.35$.
 Related Articles
 The numbers of children in 10 families of a locality are 2, 4, 3, 4, 2, 3, 5, 1, 1, 5. Find the mean number of children per family.
 Children in Homeless Families
 Children Living in HIV Families
 The following table gives the number of branches and number of plants in the garden of a school.No. of branches ($x$):23456No. of plants ($f$):4943573813Calculate the average number of branches per plant.
 1500 families with 2 children were selected randomly and the following data were recorded:If a family is chosen at random\n
 $1500$ families with $2$ children were selected randomly, and the following data were recorded:Number of girls in a family$2$$1$$0$Number of families$475$$814$$211$Compute the probability of a family, chosen at random, having$( i)\ 2$ girls $( ii)\ 1$ girl $( iii)$ No girlAlso check whether the sum of these probabilities is $1$.
 In the first proof reading of a book containing 300 pages the following distribution of misprints was obtained:No .of misprints per pages ($x$):012345No. of pages ($f$):1549536951Find the average number of misprints per page.
 In a family of $3$ children calculate the probability of having at least one boy.
 The following distribution gives the number of accidents met by 160 workers in a factory during a month.No. of accidents ($x$):01234No. of workers ($f$):70523431Find the average number of accidents per worker.
 A group of children in a n orphanage are given 72 bedsheet 144 dresses and 216 handkerchiefs . What is the largest possible number of children in orphanage?
 The given pie chart shows the result of a survey carried out to find the modes of travel used by children to go to school.$( a)$. What is the most common mode of transport?$( b)$. What fraction of children travel by car?$( c)$ If $18$ children travel by car, how many children took part in the survey?$( d)$ By which two modes of transport are equal number of children travelling?"\n
 Expression of Anger in Children
 The following data relates to the expenditure of the families \( A \) and \( B \) per month.
 Family and Systemic Influences on Children
 Socialisation of Children Through Media
Kickstart Your Career
Get certified by completing the course
Get Started