# 6.2 Frequency tables and cumulative frequency

Good morning!
Schedule:
• Learning goals
• Frequency tables
• Modal class and median
• Homework
1 / 24
Slide 1: Tekstslide
WiskundeMiddelbare schoolvwoLeerjaar 6

In deze les zitten 24 slides, met interactieve quizzen en tekstslides.

## Onderdelen in deze les

Good morning!
Schedule:
• Learning goals
• Frequency tables
• Modal class and median
• Homework

#### Slide 1 -Tekstslide

Learning goals
At the end of this lessons I can:
• Find the mode and median from a grouped frequency table
• Draw up a grouped frequency table from a set of data
• Calculate the cumulative frequency in a frequency table

#### Slide 2 -Tekstslide

A
The maximum value is 18
B
If choosing a random value there is a 75% chance it will be larger than 9
C
The mean is 12
D
The data is positively skewed

#### Slide 3 -Quizvraag

Frequency Tables
Time spend, x (min)
Frequency
Cumulative frequency
0 ≤  x < 30
30 ≤  x < 60
60 ≤  x < 90
90 ≤  x < 120
120 ≤  x < 150
150 ≤  x < 180
Time spent on Youtube per day by MP4's

#### Slide 4 -Tekstslide

Frequency Tables
Time spend, x (min)
Frequency
Cumulative frequency
0 ≤  x < 30
6
6
30 ≤  x < 60
4
10
60 ≤  x < 90
3
13
90 ≤  x < 120
0
13
120 ≤  x < 150
2
15
150 ≤  x < 180
1
16
Time spent on Youtube per day by MP4's

#### Slide 5 -Tekstslide

Grouped frequency tables
To determine the class width for your table:
Divide the range by the amount of classes you want, then round the answer UP

Start value:
Choose a start value less than or equal to your smallest value

#### Slide 6 -Tekstslide

Grouped frequency tables
To determine the class width for your table:
Divide the range by the amount of classes you want, then round the answer UP

Start value:
Choose a start value less than or equal to your smallest value

Rule of thumb:
20 or less data values     5 classes
21-50 values                      10 classes
51-100 values                     15 classes
100 or more                       20 classes

#### Slide 7 -Tekstslide

Grouped frequency tables
Student grades: 64, 68, 73, 75, 78, 79, 81, 83, 83, 84, 89, 90, 91, 94, 96, 97
1. Range =
2. n = 16
3. How many classes?
4. Class width =
5. Start value

#### Slide 8 -Tekstslide

Grouped frequency tables
Student grades: 64, 68, 73, 75, 78, 79, 81, 83, 83, 84, 89, 90, 91, 94, 96, 97
1. Range = 97-64 = 33
2. n = 16
3. I want 5 classes
4. Class width =
5. Start value can be 64 or 63
5337
Frequency
Cumulative frequency
64 ≤ x < 71
2
2
71 ≤ x < 78
2

#### Slide 9 -Tekstslide

1, 2, 5, 3, 3, 2, 2, 1, 2, 1, 1, 4, 3

What is the correct choice
for class ?
Number of pets:
# of pets, x
frequency
cumulative
frequency
a
8
8
2 < x ≤ 4
b
12
4 < x ≤ 6
1
c
a
A
1 < x ≤ 3
B
0 < x ≤ 2
C
2 < x ≤ 6
D
0 < x ≤ 4

#### Slide 10 -Quizvraag

1, 2, 5, 3, 3, 2, 2, 1, 2, 1, 1, 4, 3

What is the correct
frequency for ?
Number of pets:
# of pets, x
frequency
cumulative
frequency
a
8
8
2 < x ≤ 4
b
12
4 < x ≤ 6
1
c
b
A
4
B
5
C
6
D
7

#### Slide 11 -Quizvraag

1, 2, 5, 3, 3, 2, 2, 1, 2, 1, 1, 4, 3

What is the correct
cumulative frequency for ?
Number of pets:
# of pets, x
frequency
cumulative
frequency
a
8
8
2 < x ≤ 4
b
12
4 < x ≤ 6
1
c
c
A
1
B
20
C
4
D
12

#### Slide 12 -Quizvraag

Modal class
What do you think the modal class is?
# of pets, x
frequency
cumulative
frequency
0 < x ≤ 2
8
8
2 < x ≤ 4
4
12
4 < x ≤ 6
1
13

#### Slide 13 -Tekstslide

Modal class
The modal class  is the class with the highest frequency

# of pets, x
frequency
cumulative
frequency
0 < x ≤ 2
8
8
2 < x ≤ 4
4
12
4 < x ≤ 6
1
13

#### Slide 14 -Tekstslide

Modal class
Time spend, x (min)
Frequency
Cumulative frequency
5 < x ≤ 20
7
7
20 < x ≤ 35
4
11
35 < x ≤ 50
2
13
50 < x ≤ 65
5
18
65 < x ≤ 80
0
18
80 < x ≤ 95
1
19
Time spent on math homework
Modal class:

#### Slide 15 -Tekstslide

Median value
# of pets, x
frequency
cumulative
frequency
0 < x ≤ 2
8
8
2 < x ≤ 4
4
12
4 < x ≤ 6
1
13
The median is the                th
value.

=
2(n+1)
2(n+1)

#### Slide 16 -Tekstslide

Median value
Time spend, x (min)
Frequency
Cumulative frequency
5 < x ≤ 20
7
7
20 < x ≤ 35
4
11
35 < x ≤ 50
2
13
50 < x ≤ 65
5
18
65 < x ≤ 80
0
18
80 < x ≤ 95
1
19
Find the class with the median value.

#### Slide 17 -Tekstslide

Median value
Time spend, x (min)
Frequency
Cumulative frequency
5 < x ≤ 20
7
7
20 < x ≤ 35
4
11
35 < x ≤ 50
2
13
50 < x ≤ 65
5
18
65 < x ≤ 80
0
18
80 < x ≤ 95
1
19
Find the class with the median value.

#### Slide 18 -Tekstslide

Time spend, x, (min)
Frequency
Cumulative frequency
10
10
3
13
2
15
0
15
1
16
Modal class =

Class with median value =
Time spent on Instagram
0 ≤ x < 25
25 ≤ x < 50
50 ≤ x < 75
75 ≤ x <100
100 ≤ x < 125

#### Slide 19 -Sleepvraag

Modal class
Class with median value

#### Slide 20 -Sleepvraag

Grouped frequency tables
Cumulative frequency
4
10
18
24
30
2(30+1)th
Median class
Value

= 15.5 th value

#### Slide 21 -Tekstslide

Grouped frequency tables
How would you estimate the range in a grouped frequency table?

#### Slide 22 -Tekstslide

Grouped frequency tables