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2-2 example9

# 2-2 example9 - Student Grady Silnonton Colu'se Mathll9...

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Unformatted text preview: Student: Grady Silnonton Colu'se: Mathll9: Elementary Statistics - Spring 2010 - CRN: 49239 Instructor: Shawn Pan-'ini - 16 weeks Date: 2.518.510 Book: T1'iola: Elementary Statistics. Me Time: 1 1 :03 AM The data represents the body mass index (BMI) values for 20 females. 17.7 335 2 1 _1 25.2 24.2 Construct a frequency distribution beginning with a lower class limit of15.0 29 9 19 1 18 3 27 7,. 22 g and use a class width of 6.0. Does the frequency distribution appear to be I I I I I roughly a normal distribution? 19'2 26'] 23'4 317 33'? 21.5 44.9 23.?r 28.2 28.2 First decide on the number of classes you want. The formula for ﬁnding the class width is given below. _ ( maximum value) — ( minimum value) Class Width 2-“ —. number ot classes Since the class width, maximum value, and minimum value are given, determine the number of classes. 44.9 - 12.7 6.0 a! —, number ot classes number ofclasses as 4.53 a! 5 Use the lower limit of the ﬁrst class and the class width to ﬁll in the ﬁrst class. Body Mass Index Frequency 1 5 0-209 ? Using the lower limit of the first class and the class width, proceed to list the other lower class limits. (Add the class width to the starting point to get the second lower class limit. Add the class width to the second lower class limit to get the third, and so on.) Now ﬁll in the next class. Add the class width to the starting point to get the second lower class limit. Add the class width to the ﬁrst upper class limit to get the second upper class limit. Body Mass Index Frequency 15.0-20.9 ? 21.0-26.9 ? The remaining three classes are given below. Body Mass Index Frequency Body Mass Index Frequency 15.0-20.9 ? 33.0-38.9 ’3' 21.0-26.9 ‘3’ 39.0-44.9 ‘3' 22.0-32.9 ? To determine the frequencies, go through the data set putting a tally in the appropriate class for each data value. Use the tally marks to ﬁnd the total frequency for each class. Start with the ﬁrst frequency. There are 4 numbers between 15.0 and 20.9. Page 1 Student: Grady Sinlonton Colu'se: Mathll9: Elenlentaiy Statistics - Spring 2010 - CRN: 49239 Instructor: Shawn Pan-'ini - 16 weeks Date: 2.518.510 Book: Triola: Elenlentaiy Statistics. Me Time: 11:03 AM Body Mass Index Frequency Body Mass Index Frequency 15.0-20.9 4 33.0-38.9 ? 21.0-26.9 ‘i’ 39.0-44.9 ‘3 22.0-32.9 ? Now determine how many numbers are between 21.0 and 26.9. Body Mass Index Frequency Body Mass Index Frequency 15.0-20.9 4 33.0-38.9 ? 21.0—26.9 8 39.0—44.9 '-.’ 27.0-32.9 ? Use the same procedure to ﬁll in the remaining frequencies. Body Mass Index Frequency Body Mass Index Frequency 15.0—20.9 4 33.0—38.9 3 21 .0-26.9 8 39.0-44.9 1 27.0-32.9 4 For now, we can judge that a frequency distribution is approximately normal by determining whether it has the following features. 1. The frequencies start low, then increase to some maximum frequency, then decrease to a low frequency. 2. The distribution should be approximately symmetric, with frequencies evenly distributed on both sides of the maximum frequency. In order to be approximately normal, both conditions must be met. Therefore, the distribution is not normal because it fails condition 2. Page 2 ...
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