1. 6H Cumulative Frequency Graphs, 6I Standard Deviation
Unit 2: Descriptive Statistics
6H, 6I
4/7/ :48 PM

2. Cumulative Frequency
The cumulative frequency is simply a running total of all the individual frequencies.
Test Score
Frequency
Cumulative Frequency 93 2 87 5 7 76 3 10 75 6 16 72 12 28 68 31
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4/7/ :48 PM

3. Cumulative Frequency Curved
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4/7/ :48 PM

4. Standard Deviation
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a widely used measure of the spread (or “dispersal”), albeit non-resistant
measures the deviation between data and the mean
lowercase sigma: population’s standard deviation
x: any score
: mean
n: total number of scores
larger standard deviation data is more widely spread
closer to zero data is less widely spread
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4/7/ :48 PM

5. Notation
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6. Source: Math is Fun
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7. How can it be done using a calculator?
Ungrouped Data
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data: 2, 5, 4, 6, 7, 5, 6
Score (x) 2 -3 4 -1 5 6 1 7 35
Score (x) 2 4 5 6 7 35
Score (x) 2 -3 9 4 -1 1 5 6 7 35 16
How can it be done using a calculator?
6H, 6I
4/7/ :48 PM

8. How can it be done using a calculator?
Grouped
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Score (y)
Frequency (f) 11 3 12 4 13 5 14 2 15 8 22
Score (y)
Frequency (f)
f x y 11 3 33
5.5868 12 4 48
1.8595
7.4380 13 5 65
0.1322
0.6610 14 2 28
0.6363
0.4050
0.8100 15 8
120
1.6363
2.6777 22
294
Score (y)
Frequency (f)
f x y 11 3 33 12 4 48 13 5 65 14 2 28 15 8
120 22
294
Score (y)
Frequency (f)
f x y 11 3 33
5.5868 12 4 48
1.8595 13 5 65
0.1322 14 2 28
0.6363
0.4050 15 8
120
1.6363
2.6777 22
294
Score (y)
Frequency (f)
f x y 11 3 33 12 4 48 13 5 65 14 2 28
0.6363 15 8
120
1.6363 22
294
How can it be done using a calculator?
6H, 6I
4/7/ :48 PM

9. Guided Practice
p. 195: 2, 5, 6* p. 199: 2, 4, 5 p. 201: 2”, 4” p. 203: 1, 3 *use graph paper to make a large graph “ find mean and standard deviation by hand Read and follow all instructions. List the page and problem numbers alongside your work and answers in your notes. Use the back of the book to check your answers.
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6H, 6I
4/7/ :48 PM