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DO YOU KNOW WHAT I MEAN?

DO YOU KNOW WHAT I MEAN?. Aim: To be able to find the mean and mode from a frequency table. All: Will be able to read values from a frequency table. Most: Will be able to find the mean. Some: Will be able to comment on the mean. Data placed in a frequency table. Frequency Tables.

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DO YOU KNOW WHAT I MEAN?

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  1. DO YOU KNOW WHAT I MEAN? Aim: To be able to find the mean and mode from a frequency table. All: Will be able to read values from a frequency table. Most: Will be able to find the mean. Some: Will be able to comment on the mean.

  2. Data placed in a frequency table Frequency Tables • Convenient • Hold a large amount of data • Easy to use to find averages Here is some data on class sizes in a school. 27, 27, 28, 28, 28, 28, 29, 29, 29, 30, 30, 30, 30, 30, 31, 31, 32

  3. Mean x is variable or the data collected e.g. shoe size, weight, height etc f is the frequency

  4. Frequency Tables Calculating the mean from the frequency table. (2 x 27 + 4 x 28 + 3 x 29 + 5 x 30 + 2 x 31 + 1 x 32) 17 = 497/17 = 29.2 Mean = Original data in list form: 27, 27, 28, 28, 28, 28, 29, 29, 29, 30, 30, 30, 30, 30, 31, 31, 32 17 497 54 112 87 32 150 62 Or if entered directly into a calculator.

  5. Your Turn • Page 220 Ex 13B HOMEWORK: To get a broadsheet and a tabloid newspaper. E.g. Broadsheet: The Times, The Independent E.g. Tabloid: The Star, The Sun, Daily Mirror

  6. For the exam in 13 days! Four Averages • Aim: To be able to find the mean, median, mode and range from a frequency table. • All will be able to find the mode. • Most will be able to find the range and mean. • Some will be able to find the median

  7. Definitions • Mode is • Range is • Median is

  8. Recap the mean

  9. Izzy wizzy lets get busy • Page 206 • Ex 11F • Q1, 2, 3

  10. Score Freq 21 – 30 7 31 – 40 12 41 – 50 15 51 – 60 8 Total 42 Grouped Data Because we do not know what the exact mark for each pupil was we have to assume that each pupil obtained the middle mark in each group. E.g. in the group 31 – 40, we assume that each of the 12 pupils obtained 35.5 marks

  11. Score Freq Mid Point Calculation (f x mp) 21 – 30 7 31 – 40 12 41 – 50 15 51 – 60 8 Total 42 Grouped Data Part II To work out the mid points we add the upper and lower group limits and divide by 2. (21+30)/2=25.5 7x25.5= 178.5 (31+40)/2=35.5 12x35.5= 426 To work out the total for each group we then multiply the mid point by the frequency. (41+50)/2=45.5 15x45.5= 682.5 (51+60)/2=55.5 8x55.5= 444 1731

  12. Estimated Mean mp is the midpoint f is the frequency

  13. Score Freq Mid Point Calculation (f x mp) 21 – 30 7 31 – 40 12 41 – 50 15 51 – 60 8 Total 42 The Last Step! To find the estimated mean; (21+30)/2=25.5 7x25.5= 178.5 (31+40)/2=35.5 12x35.5= 426 (41+50)/2=45.5 15x45.5= 682.5 (51+60)/2=55.5 8x55.5= 444 1731

  14. Frequency Tables Finding the mode, median and range from the frequency table. Mode =30 (Highest frequency) Median = 29 (The middle data value) [(17 + 1)/2 = 9th data value.] Original data in list form: 27, 27, 28, 28, 28, 28, 29, 29, 29, 30, 30, 30, 30, 30, 31, 31, 32 Range = 32 – 27 = 5

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