Question

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.

Answer 1

Average (mean) $=\frac{\sum x_i{f}_i}{\sum f_i}$

$\Rightarrow$average fat number of children per family$=\frac{(0\times 10)+(1\times 21)+(2\times 55)+(3\times 42)+(4\times 15)+(5\times 7)}{150}$

$\Rightarrow$average fat number of children per family $=\frac{0+21+110+126+60+35}{150}$

$=\frac{352}{150}=2.35$