Question

Find the mean of the following data using step-deviation method:

Class	500 – 520	520 – 540	540 – 560	560 – 580	580 – 600	600 – 620
Frequency	14	9	5	4	3	5

Answer 1

Now, A = 550, h = 20, Ʃ f_i = 40 and Ʃ (f_i × u_i) = -12

= 550 – 6 

= 544 

∴ \(\bar{x}\) = 544