Question

The H.M. of following freq. dist. is

$x_i$	3	6	9	12
$f_i$	1	2	3	4

• A. 9
• B. 3
• C. 7.5
• D. none of these

Answer 1

The correct option is C 7.5

We know H.M of any frequency distribution is give by, $\frac{\sum f_i}{\sum \frac{f_i}{x_i}}$

$\therefore$ Required H.M $=\frac{1+2+3+4}{\frac{1}{3}+\frac{2}{6}+\frac{3}{9}+\frac{4}{12}}=\frac{10}{\frac{4}{3}}=\frac{30}{4}=7.5$