Examples for Summary of CH1&2

Examples for Summary of CH1&2 - Example 1 The...

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Example 1 The article “Hydrogeochemical Characteristics of Groundwater in a Mid-Western Coastal Aquifer System” (S. Jeen, J. Kim, et al., Geosciences Journal, 2001: 339-348) presents measurements of various properties of shallow groundwater in a certain aquifer system in Korea. Following are measurements of electrical conductivity (in microsiemens per centimeter) for 23 water samples. 2099 528 2030 1350 1018 384 1499 1265 375 424 789 810 522 513 488 200 215 486 257 557 260 461 500 a. Find the mean and the standard deviation. b. Find the median, the first quartile, and the third quartile. c. Construct a dot-plot.
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Solution (a) The mean is (2099+528+2030+1350+1018+384+1499+1265+375+424+789+810+522+513+488+200+215+486+257+557+260 +461+500)/23 = 740.43 μ S/cm The variance is s 2 =[2099 2 +528 2 +2030 2 +1350 2 +1018 2 +384 2 +1499 2 +1265 2 +375 2 +424 2 +789 2 +810 2 +522 2 +513 2 +488 2 +200 2 +215 2 +48 6 2 +257 2 +557 2 +260 2 +461 2 +500 2 -23(740.43 2 )]/22 = 302320.26 The standard deviation is s = 302320.26 0.5 = 549.84 (b) The 23 values, arranged in increasing order, are: 200, 215, 257, 260, 375, 384, 424, 461, 486, 488, 500, 513, 522, 528, 557, 789, 810, 1018, 1265, 1350, 1499, 2030, 2099 the median is the 12th value, which is 513 μ S/cm 0.25(24) = 6. Therefore, when the numbers are arranged in increasing order,
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Examples for Summary of CH1&2 - Example 1 The...

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