Biologists are investigating if their efforts to prevent erosion on the bank of a stream have been statistically significant.

Biologists are investigating if their efforts to prevent erosion on the bank of a stream have been statistically significant. For this stream, a narrow channel width is a good indicator that erosion is not occurring. Test the claim that the mean width of ten locations within the stream is greater than 3.7 meters. Assume that a simple random sample has been taken, the population standard deviation is not known, and the population is normally distributed. Use the following sample data: 3.3 3.3 3.5 4.9 3.5 4.1 4.1 5 7.3 6.2 What is the P-value associated with your test statistic? Report your answer with three decimals, e.g., .987

Biologists, researching the effects of adding limestone sand as buffer for acid rain effects in streams,

monitored the pH levels of two streams each month for 36 months. The first stream had a mean pH level of 6.8 with a standard deviation of 2.3. The control stream had a mean pH level of 9.2 with a standard deviation of 1.5. Assume a .05 significance level for testing the claim that the mean pH of the first stream was less (more acidic) than the mean pH of the control stream. Also, assume the two samples are independent simple random samples selected from normally distributed populations, but do not assume that the population standard deviations are equal. Find the t test statistic. Give your answer with two decimals, e.g., 9.87