Question

Find standard deviation from the following data: Class 0-4 4-8 8-12 12-16 16-20 Frequency 10 2 3 3 2? please explain in step by step please its urgent !​

Answer 1

I x

i

f

i

f

i

x

i

(x

i

−

x

)

2

f

i

(x

i

−

x

)

2

4−8 6 3 18 49 147

8−12 10 6 60 9 54

12−16 14 4 56 1 4

16−20 18 7 126 25 175

∑f

i

=20 ∑f

i

x

i

=260 ∑(x

i

−

x

)

2

=84 ∑f

i

(x

i

−

x

)

2

=380

⇒

x

=

∑f

i

∑f

i

x

i

=

20

260

=13

⇒ Variance(σ

2

)

∑f

i

∑f

i

(x

i

−

x

)

2

=

20

380

=19