Question

32. Find the mean of the following data, by direct method.
C.I.
1-5
5-9
9-13
13-17
17-21
f
4
3
5
7
1

n"20​

Answer 1

Answer:

Class Interval frequency(f) Mid value (x) f(x) cf

1-5 7 3 21 7

5-9 2 7 14 9

9-13 2 11 22 11

13-17 8 15 120 19

17-21 1 19 19 20

n = 20 ∑f(x) = 196

Mean \bar{x}=\frac{\sum fx}{n}

x

ˉ

=

n

∑fx

=\frac{196}{20}=

20

196

Mean = 9.8