Find the mean of the following distribution by step deviation met… - Vidyadip

Question

Find the mean of the following distribution by step deviation method:

Class interval	$20 - 30$	$30 - 40$	$40 - 50$	$50 - 60$	$60 - 70$	$70 - 80$
Frequency	$10$	$6$	$8$	$12$	$5$	$9$

✓

Answer

Here,
A = Assumed mean $= 55$
$h = 10$
$\therefore \text { Mean } \overline{ X }= A +\frac{\sum f \mu}{\sum f} \times h $
$=55+\frac{(-27)}{50} \times 10$
$= 55 - 5.4$
$= 49.6.$

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