Cumulative Frequency
A cumulative frequency diagram creates a running total of the amounts within a table.
E.g.:
Length (cm) Frequency (F) (CF) Cumulative Frequency
30 < L < 35 4 4
35 < L < 40 10 14
40 < L < 45 11 25
45 < L < 50 12 37
50 < L < 55 3 40
Total 40
Always begin with CF as 4 in the first row.
Mode of this table - (Most common) range of ‘45 < L < 50’ (answer).
Mean (overall average) of this table -
Find out midpoints of each of the lengths, e.g. - ‘30 < L < 35’ midpoint = 32.5
Times the midpoint with the Frequency (F), e.g. - 32.5 × 4
o Do the same for all of the other rows,
- As total average / total frequency: mean = 1700/40 = 42.5 (answer)
Median (middle value) -
Total = 40 Midpoint = 40/2 = 20
20 Falls under the grp ‘(40 < L < 45).
Answer - **40 < L < 45**
Number of drawing pins frequency C.F
29 2 58 2
30 5 150 2+5 = 7
31 2 62 7+2 = 9
32 1 32 9+1= 10
Total - 10 302
Mean - In this kind of table,
A cumulative frequency diagram creates a running total of the amounts within a table.
E.g.:
Length (cm) Frequency (F) (CF) Cumulative Frequency
30 < L < 35 4 4
35 < L < 40 10 14
40 < L < 45 11 25
45 < L < 50 12 37
50 < L < 55 3 40
Total 40
Always begin with CF as 4 in the first row.
Mode of this table - (Most common) range of ‘45 < L < 50’ (answer).
Mean (overall average) of this table -
Find out midpoints of each of the lengths, e.g. - ‘30 < L < 35’ midpoint = 32.5
Times the midpoint with the Frequency (F), e.g. - 32.5 × 4
o Do the same for all of the other rows,
- As total average / total frequency: mean = 1700/40 = 42.5 (answer)
Median (middle value) -
Total = 40 Midpoint = 40/2 = 20
20 Falls under the grp ‘(40 < L < 45).
Answer - **40 < L < 45**
Number of drawing pins frequency C.F
29 2 58 2
30 5 150 2+5 = 7
31 2 62 7+2 = 9
32 1 32 9+1= 10
Total - 10 302
Mean - In this kind of table,
