1. Calculate Octile-5 from the following grouped data

X	Frequency
0	1
1	5
2	10
3	6
4	3

Solution:

`x`	Frequency `f`	`cf`
0	1	1
1	5	6
2	10	16
3	6	22
4	3	25
---	---	---
	`n = 25`	--

Here, `n = 25`

`"Octile"_5 = ((5(n+1))/8)^(th)` value of the observation

`=((5*26)/8)^(th)` value of the observation

`=(16.25)^(th)` value of the observation

`=3`

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2. Calculate Octile-3 from the following grouped data

X	Frequency
10	3
11	12
12	18
13	12
14	3

Solution:

`x`	Frequency `f`	`cf`
10	3	3
11	12	15
12	18	33
13	12	45
14	3	48
---	---	---
	`n = 48`	--

Here, `n = 48`

`"Octile"_3 = ((3(n+1))/8)^(th)` value of the observation

`=((3*49)/8)^(th)` value of the observation

`=(18.375)^(th)` value of the observation

`=12`

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