Question

Calculate mean deviation from mean
and standard deviation from the
following data:
Marks Obtained
No. of Students
0 - 10
10-20
20-30
30-40
40 - 50
50-60
60 - 70
g
16
23
25
12
8
ㅋ​

Answer 1

CI f

i

Mid−value

x

i

f

i

x

i

∣x

i

−

x

∣ f

i

∣x

i

−

x

∣

10−20 2 15 30 30 60

20−30 3 25 75 20 60

30−40 8 35 280 10 80

40−50 14 45 630 0 0

50−60 8 55 440 10 80

60−70 3 65 195 20 60

70−80 2 75 150 30 60

∑f

i

=40

∑f

i

x

i

=

1800 ∑f

i

∣x

i

−

x

∣=

400

⇒

x

=

∑f

i

∑f

i

x

i

=

40

1800

=45

⇒ Mean deviation about mean =

∑f

i

∑f

i

∣x

i

−

x

∣

=

40

400

=10