9
0.7 points
Confidence Interval for the Difference in Two Population Means
The seagrass Thalassia testudinum is an integral part of the Texas coastal ecosystem. Essential to the growth of T. testudinum is ammonium. Researchers K. Lee and K.
Dunton of the Marine Science Institute of the University of Texas at Austin noticed that the seagrass beds in Corpus Christi Bay were taller and thicker than those in
Lower Laguna Madre.
They compared the sediment ammonium concentrations in the two locations and published their findings in Marine Ecology Progress Series (Vol. 196, pp. 39-48).
Following are the summary statistics on sediment ammonium concentrations, in micromoles, obtained by the researchers.
Corpus Christi Bay: xbar1-116, s1-85, n1-70
Lower Laguna Madre: xbar2-34, s2-9, n2 = 40
When calculating the 98% confidence interval for the difference in the average sediment ammonium concentrations between Corpus Christi Bay area and the Lower
Laguna Madre area:
the estimate is X1-X2.
the standard error is 10.26 and
the margin of error is 23.91.
What is the value of the Lower Confidence Limit (LCL) for this interval? Round to the 100ths place. [1]
What is the value of the Upper Confidence Limit (UCL) for this interval? Round to the 100ths place. [2]
[1]= type your answer...
,[2] type your answer...
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