Mid1_WI04_SLN

Mid1_WI04_SLN - ST A T 4 2 7 P r of . Goe l S o lu t io n t...

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1 of 2 pages STAT 427 Solution to Midterm I Winter, 2004 Prof. Goel MWF 10:30 - 11.20 NOTES: This is a closed book examination. You can use your own calculator and a single-sided 8.5” x 11” crib sheet. There are four problems worth a total of 50 points. You must explain each step in your answer to get partial credits. Good Luck! Problem 1. [10 points] Environmental impact studies on the quality of water often measure the level of chemical toxicants by the LC50, the concentration lethal to 50% of the organisms of a particular species under a given set of conditions and specified time period. Two common toxicants are methyl parathion (MP) and Baytex. LC50 measurements on water samples for each of these toxicants are as follows: MP 3.1, 4.7, 5.2, 2.8, 5.2, 5.3, 5.7, 6.6, 5.7, 7.1, 9.0, 8.9 Baytex 0.9, 1.2, 1.3, 1.4, 1.3, 1.6, 1.5, 1.6, 1.7, 1.9, 3.4, 2.4 (i) [6 points] Calculate the medians, the lower and upper quartiles of the above data sets. First one must order the data from the smallest to the largest as follows: MP 2.8, 3.1, 4.7, 5.2, 5.2, 5.3, 5.7, 5.7, 6.6, 7.1, 8.9, 9.0 Baytex 0.9, 1.2, 1.3, 1.3, 1.4, 1.5, 1.6, 1.6, 1.7, 1.9, 2.4, 3.4 Since n = 12, the median is the average of 6 th and 7 th items, the lower quartile is the average of 3 rd and 4 th
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Mid1_WI04_SLN - ST A T 4 2 7 P r of . Goe l S o lu t io n t...

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