Question

8. The frequency distribution of marks obtained by
40 students of a class is as under:
Calculate the Arithmetic mean.
Marks 0-8 8-16 16-24 24-32 32-40 40-48
Students 5
3
10
16
4
2
(ICSE​

Answer 1

Step-by-step explanation:

Answer:-

Given:-

Σf

i

=40, Mean = 35.75

Converting the given table into frequency distribution table with class interval of width 10 we get:

Marks No. of

students

f

i

x

i

f

i

.x

i

10-20 40-34=6 15 90

20-30 34-26=8 25 200

30-40 26-f

1

35 910−35f

1

40-50 f

1

−6 45 45f

1

−270

50-60 6−f

2

55 330−55f

2

60-70 f

2

−1

65 65f

2

−1

70-80 1-0=1 75 75

80-90 0-0=0 85 0

Σf

i

=40 Σf

i

.x

i

=1270+10f

1

+10f

2

Mean =

Σf

i

Σf

i

.x

i

=

40

1270+f

1

+f

2

=35.75

1270+f

1

+f

2

=1430

10f

1

+10f

2

=160

f

1

+f

2

=16⟶eq

n

(i)

Given:-

f

2

f

1

=

1

3

⇒f

1

=3f

2

⟶(ii)

From (i)and(ii), we get:

3f

2

+f

2

=16

4f

2

=16

f

2

=

4

16

f

2

=4

f

1

=3f

2

=3×4=12

Answer 2

Answer:

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