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Advanced Math Topics. 2.4 Cumulative Frequency Histograms & Polygons If you do not use stem and leaf add the part about misleading graphs to this ppt. Normal Curve. A radar set up on Highway 580 for one hour clocked and recorded car speeds between 52 and 82 mph. The
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Advanced Math Topics 2.4 Cumulative Frequency Histograms & Polygons If you do not use stem and leaf add the part about misleading graphs to this ppt
Normal Curve A radar set up on Highway 580 for one hour clocked and recorded car speeds between 52 and 82 mph. The scatter plot is shown below. How will the graph look? . . . . . . . . This is an example of a normal curve (normal distribution), Also known as the “Bell Curve.” 1800 . F R E Q U E N C Y . . 1600 . . 1400 . . Many things that occur in nature have a normal distribution. . 1200 . . . . . 1000 . . . 800 . . . 600 . 400 200 76 78 66 68 70 72 74 80 82 52 54 56 58 60 62 64
Would these have a normal distribution? The useful life of an auto battery with time along the horizontal axis. Yes! The number of students per class with # of students on the horizontal axis. Depends, some classes(PE) may throw it off)! The attendance at AT&T Park for Giants with the amount of people on the horizontal axis. No, the attendance is too consistent! http://sports.espn.go.com/mlb/attendance
Steps to Create a Cumulative Frequency Histogram • Create a new column “Cumulative Total.” Add all previous • frequencies and put this number in the row. 2) Follow the steps to create a histogram
Cumulative frequency histogram: a histogram displaying accumulated figures Cumulative Frequency Histogram How many recruits weighed 170 lbs. or less? Weights of 250 Army Recruits Cumulative Frequency Weight (lbs.) Frequency 280 250 240 23 23 131-140 194 200 43 23 + 43 = 66 141-150 Cum. Freq. 160 125 59 151-160 66 + 59 = 125 120 69 161-170 125 + 69 = 194 80 66 56 171-180 194 + 56 = 250 40 23 131-140 151-160 171-180 Sometimes we ask questions like… “How many are less than or equal to a certain measurement?” 141-150 161-170 Weight We can answer this by accumulating the frequencies.
Steps to Create a Cumulative Frequency Polygon • Find the cumulative total for each row 2) Create axis and intervals just like a histogram 3) Place a point for each cumulative frequency on the right side of the interval Why the right? Because the frequency includes all numbers at or below the highest number in the interval 4) Connect the points
Cumulative Frequency Cumulative Frequency Polygon 23 23 + 43 = 66 66 + 59 = 125 . 280 125 + 69 = 194 240 250 . 194 + 56 = 250 200 194 Cum. Freq. . 160 A line graph that answers the question “How many recruits weigh less than or equal to a certain weight?” 125 120 . Create the same axes and scales, place a point on the upper limit for each interval at its cumulative frequency and connect them. 80 . 66 . 40 23 There were 125 recruits 160 lbs. or under. 131-140 151-160 171-180 141-150 161-170 Weights There were 0 recruits 130 lbs. or under.
Assignment P. 61 – 67 #3, 4, 12, 14a, 14b, 15 • Together P. 67 #14a We have 3 missing protractors