1 A stream has been monitored weekly for a number of years, and the total dissolved solids in the stream averages 40 parts per million and is constant throughout the year. Following a recent change in land use in the drainage basis of the steam, a fluvial geomorphologist finds that the mean parts per million of dissolved solids in a 25-week sample to be 52 with a standard deviation of 32. Has there been a change in the average level of dissolved solids in this stream?
2 An exhaustive survey of all users of a wilderness park taken in 1960 revealed that the average number of persons per party was 2.6 In a random sample of 25 parties in 1985, the average was 3.2 persons with a standard deviation of 1.08. a. Test the hypothesis that the number of persons per party has changed in the last 25 yr. b. Determine the PROB-VALUE of your test
3 A manufacturer of barometers believes that the production process yields 2.2 percent defectives. In a random sample of 250 barometers, 7 are defective. a. Test whether the manufacturer’s belief is confirmed by this sample, calculate the PROB-VALUE for a test of hypothesis of b. At which of the following significance levels will the null hypothesis be rejected? (i) 0.20; (ii) 0.10; (iii)0.05; (iv) 0.01; and (v) 0.001
4 The average score of geography majors on a standard graduate school entrance examination is hypothesized to be 600: that is, ramdom sample of n=75 students is selected. The decision rule used to reject is a. Reject or
Assume that the standard deviation is 100 and is normally distributed. Find for this test.
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