Question

4. Calculate mean from the following data using step deviation method :
X:15 35 45 65 85 70 50 40 25 15
​

Answer 1

Answer:

X Mid point (x)  Frequency (F)  i=class  interval width  A=22.5 Assumed mean  d'=

i

x−A

​

  fd'

0-5  2.5  3  5  22.5  -4  -12

5-10  7.5  5  5  22.5  -3  -15

10 -15 12.5  7  5  22.5  -2  -14

15-20  17.5  8  5  22.5  -1  -8

20-25  22.5=A  10  5  22.5  0  0

25-30  27.5  11  5  22.5  1  11

30-35  32.5  14  5  22.5  2  28

35-40  37.5  19  5  22.

5  3  57

40-45  42.5  15  5  22.5  4  60

45-50  47.5  13  5  22.5  5  65

   Σf=105        Σfd

′

=172

Explanation:

Answer 2

Answer:

mean = sum of observations/number of observations

mean = 15+35+45+65+85+70+50+40+25+15/10

mean = 445/10

mean = 44.5