6.2 Frequency tables and cumulative frequency

Good morning!
Schedule: 
  • Learning goals 
  • Frequency tables 
  • Modal class and median
  • Homework 
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Slide 1: Slide
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This lesson contains 24 slides, with interactive quizzes and text slides.

Items in this lesson

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

Slide 1 - Slide

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 - Slide


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 - Quiz

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 - Slide

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 - Slide

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 - Slide

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 - Slide

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 - Slide

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
Grades
Frequency 
Cumulative frequency
64 ≤ x < 71
2
2
71 ≤ x < 78
2

Slide 9 - Slide

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 - Quiz

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 - Quiz

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 - Quiz

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 - Slide

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 - Slide

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 - Slide

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 - Slide

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 - Slide

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 - Slide

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 - Drag question

Modal class
Class with median value

Slide 20 - Drag question

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

= 15.5 th value 


Slide 21 - Slide

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

Slide 22 - Slide

Grouped frequency tables

Slide 23 - Slide

Take out your diaries/notebook


Homework for Tuesday 14-3-2023:
                 p. 329-330: Practice 1  #1, 2, 3 , 4
             



Slide 24 - Slide