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:

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
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