Question-(5 points) TCDD contamination. Tetrachlorodibenzo-p-dioxin (TCDD) is a

Question

Question-(5 points) TCDD contamination. Tetrachlorodibenzo-p-dioxin (TCDD) is a highly toxic substance found in industrial wastes. A study was conducted to determine the amount of TCDD present in the tissues of bullfrogs inhabiting the Rocky Branch Creek in central Arkansas, an area known to be contaminated by TCCD (Chemosphere, Feb, 1986). The level of TCCD (in parts per trillion) was measured in several specific tissues of four female bull frogs; the ratio of TCDD in the tissue to TCCD in the leg muscle of the frog was recorded for each. The relative ratios of contaminant for two tissues, the liver and the ovaries, are given for each of the four frogs in the accompanying table. According to the researchers, "The data set suggests that the (mean) relative level of TCCD in the ovaries of female frogs is higher than the (mean) level in the liver of the frogs." Test this claim using = 0.05. Fro Liver-1.04.64.32.2 | Ovaries 34.2 41.2 32.5 26.2

Explanation / Answer

The mean of the TCDD levels in the liver = 13.025, and mean of TCDD levels in the ovaries = 33.525 and the std.dev are s1 = 1.72 and s2 = 11.78

Now the null Hyp H0 : u1-u2 =0 and the alt hyp Ha: u1-u2!=0

Now t = 33.52 - 13.02 / SQRt( s1^2/n1 + s2^2 /n2) = 33.592-13.02 / 5.95 = 3.45

Now the area to the right of the t statistic = 0.0008 = pvalue . This can be obtained using the T.Dist() function in excel

Now at alpha = 0.05 the pvalue<alpha i.e. 0.008<0.05 hence we reject the null hypothesis and conclude that the mean levels of TCDD in the ovaries of the frogs is higher thatn the mean levels in the liver of the frogs at the 0.05 sig. level

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