continuous data calculating averages with. a group of 50 nurses were asked to estimate a minute. the...
TRANSCRIPT
Continuous Data
Calculating Averages
with
A group of 50 nurses were asked to estimate a minute. The results are shown in the table.
Time (seconds) Frequency
10 < t ≤ 20 0
20 < t ≤ 30 2
30 < t ≤ 40 2
40 < t ≤ 50 9
50 < t ≤ 60 13
60 < t ≤ 70 17
70 < t ≤ 80 3
80 < t ≤ 90 2
90 < t ≤ 100 2
Example 1
Estimating a minute - nurses results
10 20 30 40 50 60 70 80 90 100 Time (seconds)
18
16
14
12
10
8
6
4
2
0
Frequency
Time (seconds) Frequency
10 < t ≤ 20 1
20 < t ≤ 30 2
30 < t ≤ 40 2
40 < t ≤ 50 9
50 < t ≤ 60 13
60 < t ≤ 70 17
70 < t ≤ 80 3
80 < t ≤ 90 2
90 < t ≤ 100 2
Use the end points of each class interval for the scale on the horizontal axis
10 20 30 40 50 60 70 80 90 100 Time (seconds)
18
16
14
12
10
8
6
4
2
0
Frequency
Estimating a minute - nurses results
Averages
• Mode – with grouped data this is called the modal group or class.
Modal group 60 < t ≤ 70
Time (seconds)
Frequency
10 < t ≤ 20 1
20 < t ≤ 30 2
30 < t ≤ 40 2
40 < t ≤ 50 9
50 < t ≤ 60 13
60 < t ≤ 70 17
70 < t ≤ 80 3
80 < t ≤ 90 2
90 < t ≤ 100 2
Estimated mean • grouped data so the mean is estimated.
Time (seconds)
Frequency
10 < t ≤ 20 0
20 < t ≤ 30 2
30 < t ≤ 40 2
40 < t ≤ 50 9
50 < t ≤ 60 13
60 < t ≤ 70 17
70 < t ≤ 80 3
80 < t ≤ 90 2
90 < t ≤ 100 2
Mid-point
15
25
35
45
55
65
75
85
95
Estimated mean = sum of mid-point x freq =
total frequencies
= 2930 = 58.6 seconds
50
Mid-point x Frequency
0
50
70
405
715
1105
225
170
190
Total 50 2930
1: Find the modal group, median and estimate the mean from the table below. 2: Draw a histogram to represent the data .
• Michelle keeps a record of the number of minutes her train is late each day. The table shows her results for a period of 50 days.
Time (seconds) Frequency
10 < t ≤ 20 1
20 < t ≤ 30
30 < t ≤ 40 1
40 < t ≤ 50 5
50 < t ≤ 60 11
60 < t ≤ 70 4
70 < t ≤ 80
80 < t ≤ 90
90 < t ≤ 100