Q11 of 174 Page 585

Use the step-deviation method to find the arithmetic mean from the following data.

X

18

19

20

21

22

23

24

F

170

320

530

700

230

140

110

Let the assumed mean be A = 21

= h = x₂ – x₁ = 19 – 18 = 1

Thus, we prepare the table given below:

We Know that,

Mean =

Hence, The Mean value of given distribution = 20.62.

Use the assumed-mean method to find the mean weekly wages from the data given below.

Weekly wages (in Rs)	800	820	860	900	920	980	1000
No. of workers	7	14	19	25	20	10	5

Use the assumed-mean method to find the mean height of the plants from the following frequency-distribution table.

Height in cm (x_i)	61	64	67	70	73
No. of plants (f_i)	5	18	42	27	8

The table given below gives the distribution of villages and their heights from the sea level in a certain region.

Height (in meters)	200	600	1000	1400	1800	2200
No. of villages	142	265	560	271	89	16

Compute the mean height, using the step-deviation method.

Find the median of

(i) 2, 10, 9, 9, 5, 2, 3, 7, 11

(ii) 15, 6, 16, 8, 22, 21, 9, 18, 25

(iii) 20, 13, 18, 25, 6, 15, 21, 9, 16, 8, 22

(iv) 7, 4, 2, 5, 1, 4, 0, 10, 3, 8, 5, 9, 2

Use the step-deviation method to find the arithmetic mean from the following data.X18192021222324F170320530700230140110