Question

The mean of the following distribution is 18. Find the frequency f of the class 19 – 21. Class 11-13 13-15 15-17 17-19 19-21 21-23 23-25 Frequency 3 6 9 13 f 5 4

Answer 1

Hope this will help YOU

F=8

For explanations see attachment

Answer 2

Answer:

ANSWER

Class Interval Mid Value

x

i

Frequency

f

i

f

i

x

i

11 - 13 12 3 36

13 - 15 14 6 84

15 - 17 16 9 144

17 - 19 18 13 234

19 - 21 20 f 20 f

21 - 23 22 5 110

23 - 25 24 4 6

∑f=40+f ∑fx=704+20f

Given : Mean =18

We know, Mean (

x

)=

Σf

Σfx

⟹18=

40+f

704+20f

⟹18(40+f)=704+20f

⟹720+18f=704+20f

⟹720−704=20f−18f

⟹2f=16

⟹f=8

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