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Chapter 3 Cumulative Test Sample 30 people spent on books ($) 156 150 109 98 136 170 178 195 110 191 187 119 104 160 132 117 111 120 103 123 153 91 162.

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Presentation on theme: "Chapter 3 Cumulative Test Sample 30 people spent on books ($) 156 150 109 98 136 170 178 195 110 191 187 119 104 160 132 117 111 120 103 123 153 91 162."— Presentation transcript:

1 Chapter 3 Cumulative Test Sample 30 people spent on books ($) 156 150 109 98 136 170 178 195 110 191 187 119 104 160 132 117 111 120 103 123 153 91 162 93 118 127 90 181 110 116

2 1) qualitative or quantitative and level of measurement Data is quantitative Data is ratio (there is a true 0)

3 2) Method of data collection. Sampling technique Use a survey Collect data using random sampling (randomly chosen people) If data were systematic or convenience the sample might not be representative of the amount people spent on boods.

4 3. Make frequency distribution with 5 classes. Include class limits, midpoints, frequencies, boundaries, relative freq and cumulative freq.

5 Frequency histogram and polygon

6 Stem and leaf 9 : 0138 10 : 349 11 : 0016789 12 : 037 13 : 26 14 : 15 : 036 16 : 02 17 : 08 18 : 17 19 : 15

7 Box and whisker (boxplot)

8 Mean median and mode Mean= $133.67 Median= $121.50 Mode = $100.50 These are statistics because they describe a sample

9 Range, variance and standard deviation Range = $195 -90 = $105 Variance = 1040.5 standard deviation = $32.26 The range is larger than 3 standard deviations.

10 Probability spending < $120 Frequency estimate = 14/30=.467 Prob randomly selecting person who spent more than $120. There are 15 such people in the sample. So Prob=0.5

11 Prob person spent $160 These are mutually exclusive events (person cannot do both). So the probability is the sum of the probabilities of individual events which is 14/30 + 7/30 = 21/30 =.7

12 5 person sample. Prob (at least one spent > $175) Pr(any person spent > $175) = 5/30 =.1667 Pr(at least 1 person spent > $175) = 1 - Pr(no people spent > $175) Assume samples are independent (i.e not from the 30 people sampled, which would be a dependent sample Pr(one person > $175) =.8333 Pr(1 or more) = 1 -.833^5 =.598 If dependent then = 1 - 25*24*23*22*21/(30*29*28*27*26) =.627

13 How many ways can 5 respondents be resampled from 30? Order is not important so it is number of combinations of 30 things taken 5 at a time This is 142506


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