Solution:

 x f c.f 5 6 6 10 10 16 15 15 31 20 12 43 25 6 49 30 5 54 N = 54

Solution:

 Marks Frequency c.f 30 - 40 6 6 40 - 50 6 12 50 - 60 9 21 60 - 70 4 25 70 - 80 5 30 80 - 90 6 36 90 - 100 4 40 N = 40

Solution:

 marks frequency c.f 10- 20 3 3 20 - 30 5 8 30 - 40 7 15 40 - 50 7 22 50 - 60 7 29 60 - 70 9 38 70 - 80 7 45 N = 45

Solution:

 x f c.f 40 5 5 50 10 15 60 20 35 70 12 47 80 8 55 90 5 60 N = 60

Solution:

 x f c.f 5 2 2 10 4 6 15 8 14 20 10 24 25 12 36 30 14 50 35 16 66 N = 66

Solution:

 x f c.f 5 3 3 15 8 11 25 13 24 35 10 34 45 4 38 N = 38

Solution:

 marks frequency c.f 0 -10 6 6 10 -20 8 14 20 - 30 8 22 30 - 40 5 27 40 - 50 3 30 N = 30

Solution:

 x f c.f 0 3 3 10 15 18 20 2 20 30 10 30 40 8 38 50 7 45 60 13 58 70 18 76 80 14 90

$$\therefore$$ N = 90

Solution:

 X frequency (f) cumulative frequency (c.f.) 0 15 15 20 8 23 40 13 36 80 11 47 100 1 48 120 5 53 N = 53

Solution:

 x f c.f 5 4 4 20 13 17 35 11 28 50 3 31 65 5 36 80 8 44 N = 47

Solution:

 x f c.f 0 3 3 5 8 11 10 12 23 15 15 38 20 8 46 25 7 53 30 2 55 N = 55

Solution:

 x f c.f 10 5 5 20 10 15 30 15 30 40 20 50 50 25 75 N = 75

Solution:

 x f c.f 0 2 2 10 3 5 20 8 13 30 11 24 40 8 32 50 4 36 60 5 41 N = 41