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Section_7.1[1]

Section_7.1[1] - species altitude before 1986(meters...

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Written homework for section 7.1 - using t 1. Samples were taken of mud dredged from San Francisco Bay, and tested vor toxic substances. A sample of n = 5 “cores” had average selenium content of = .47 ppm x with standard deviation s = .25 ppm. It is reasonable to assume that the distribution of selenium has a normal distribution. a. Test the claim that the average selenium content of all of the dredged muc ( μ ) was less than the EPA limit of .70 ppm. Give the null and alternate hypotheses, the value of t, the approximate value of P, and your conclusion. b. Give a 90% confidence interval for the average level of selenium in the dredged mud. (It is customary to use a confidence level below 95% for small samples, in order to make the interval narrow.) 2. Here is data from the study of the optimum altitude at which plants have been growing - this time for a random sample of n = 4 species of “woody” plants.

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Unformatted text preview: species altitude before 1986 (meters) altitude 1986 or later (meters) Acer campestre 642 660 Carpinus betulus 380 446 Daphne laureola 812 982 Viburnum lantana 941 1019 a. Find the four differences [altitude later ! altitude before]. This is the random sample of differences. b. What assumption do you need to be able to do a test or make a confidence interval using this data? c. Find the mean and standard deviation of the differences. d. Test the claim that the average difference ( μ ) in the population of all of the woody plants is positive (>0). (This would mean that all of the plants are living higher on the mountain than they had been, on the average.) Give the null and alternate hypotheses, the value of t, the approximate value of P, and your conclusion. e. Find a 90% confidence interval for the average distance all of the plants have moved up the mountain ( μ )....
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Section_7.1[1] - species altitude before 1986(meters...

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