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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 93 118 127 90 181 110 116
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1) qualitative or quantitative and level of measurement Data is quantitative Data is ratio (there is a true 0)
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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.
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3. Make frequency distribution with 5 classes. Include class limits, midpoints, frequencies, boundaries, relative freq and cumulative freq.
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Frequency histogram and polygon
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Stem and leaf 9 : 0138 10 : 349 11 : 0016789 12 : 037 13 : 26 14 : 15 : 036 16 : 02 17 : 08 18 : 17 19 : 15
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Box and whisker (boxplot)
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Mean median and mode Mean= $133.67 Median= $121.50 Mode = $100.50 These are statistics because they describe a sample
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Range, variance and standard deviation Range = $195 -90 = $105 Variance = 1040.5 standard deviation = $32.26 The range is larger than 3 standard deviations.
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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
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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
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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
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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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