Question

Find the mean of the following frequency distribution:

Class	$0-10$	$10-20$	$20-30$	$30-40$	$40-50$	$50-60$	$60-70$
Frequency	$4$	$4$	$7$	$10$	$12$	$8$	$5$

Answer 1

Class Interval	Mean Value $\left(x\right)$	Frequency $\left(f\right)$	$f\times x$
$0-10$	$5$	$4$	$20$
$10-20$	$15$	$4$	$60$
$20-30$	$25$	$7$	$175$
$30-40$	$35$	$10$	$350$
$40-50$	$45$	$12$	$540$
$50-60$	$55$	$8$	$440$
$60-70$	$65$	$5$	$325$
		$\Sigma f=50$	$\Sigma fx=1910$

Mean, $\overline{x}=\frac{\Sigma fx}{\Sigma f}$

$\Rightarrow \overline{x}=\frac{1910}{50}$

$\Rightarrow \overline{x}=38.2$

Hence, the mean is $38.2$.