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Unformatted text preview: Student: Grady Simonton Course: Math119: Elementary Statistics  Spring 2.010  CRN: 49239
Instructor: Shawn Parvini  16 weeks Date: 2/18/10 Book: Triola: Elementary Statistics, 11e
Time: 11:23 ANI Pennies made before 1983 are 97% copper and 3% zinc, whereas pennies made after 1983 are 3% copper and 97% zinc.
Listed below are the weights (in grams) of pennies from each of the two time periods. Find the mean and median for
each of the two samples, then compare the two sets of results. Before 1983: 3.1032 3.0769 3.1085 3.1281 3.1039 3.1584
After 1983: 2.4848 2.5019 2.4819 2.4999 2.4910 2.4956 The mean of a set of values is the measure of center found by adding the values and dividing the total by the number of
values. Mean = 23 w
11 (— number of sample values Start by ﬁnding the mean weight of pennies made before 1983. First add the values. Zx 3.1032 +3.0769 +3.1085 +3. 1281 + 3.1039 + 3.1584
18.6?90 grams To ﬁnd the mean, divide the sum, 18.6790, by the number of observations. In this problem there are 6 observations. 18.6790
mean = — =5 3.1132 grams The median of a data set is the measure of center that is the middle value when the original data values are arranged in
order of increasing magnitude. Start by arranging the weights of the pennies before 1983 in ascending order. 3.0769, 3.1032, 3.1039, 3.1035, 3.1281, 3.1534 If the number of values is odd, the median is the number located in the exact middle of the list. If the number of values is
even, the median is found by computing the mean of the two middle numbers. Since there are 6 observations, the data set has an even number of values. Thus, the median is the mean of the two middle observations, 3.1039 and 3.1085. 3.1039+ 3.1085
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3.1062 grams Median The mean weight of the pennies made before 1983 is 3.] 132 grams and the median weight is 3.1062 grams. Use similar methods to ﬁnd the mean and median weights of the pennies after 1983. Page 1 Student: Grady Silnonton Course: Math119: Elementary Statistics  Spring 2.010  CRN: 49239
Instructor: Shawn Parvini  16 weeks Date: 2/18/10 Book: Triola: Elementary Statistics, 11e
Time: 11:23 ANI The mean weight of the pennies made after 1983 is 2.4925 grams.
The median weight of the pennies made after 1983 is 2.4933 grams. Compare the means. If the weight has changed by more than 5% conclude that there is a considerable difference between
the means. If the weight has changed by less than 5% there is not a considerable difference between the means. Page 2 ...
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 Spring '10
 PARVINI

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