1. Continuous Data Calculating Averages with

2. A group of 50 nurses were asked to estimate a minute. The results are shown in the table. Time (seconds)Frequency 10 < t ≤ 200 20 < t ≤ 302 30 < t ≤ 402 40 < t ≤ 509 50 < t ≤ 6013 60 < t ≤ 7017 70 < t ≤ 803 80 < t ≤ 902 90 < t ≤ 1002 Example 1

3. 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 FrequencyFrequency

4. Time (seconds)Frequency 10 < t ≤ 201 20 < t ≤ 302 30 < t ≤ 402 40 < t ≤ 509 50 < t ≤ 6013 60 < t ≤ 7017 70 < t ≤ 803 80 < t ≤ 902 90 < t ≤ 1002 Use the end points of each class interval for the scale on the horizontal axis

5. 10 20 30 40 50 60 70 80 90 100 Time (seconds) 18 16 14 12 10 8 6 4 2 0 FrequencyFrequency Estimating a minute - nurses results

6. Averages Mode – with grouped data this is called the modal group or class. Modal group 60 < t ≤ 70 Time (seconds)Frequency 10 < t ≤ 201 20 < t ≤ 302 30 < t ≤ 402 40 < t ≤ 509 50 < t ≤ 6013 60 < t ≤ 7017 70 < t ≤ 803 80 < t ≤ 902 90 < t ≤ 1002

7. Estimated mean grouped data so the mean is estimated. Time (seconds) Frequency 10 < t ≤ 200 20 < t ≤ 302 30 < t ≤ 402 40 < t ≤ 509 50 < t ≤ 6013 60 < t ≤ 7017 70 < t ≤ 803 80 < t ≤ 902 90 < t ≤ 1002 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

8. 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.

9. Time (seconds)Frequency 10 < t ≤ 201 20 < t ≤ 30 30 < t ≤ 401 40 < t ≤ 505 50 < t ≤ 6011 60 < t ≤ 704 70 < t ≤ 80 80 < t ≤ 90 90 < t ≤ 100