A chemist wishes to test the effect of four chemical agents on the strength of a particular type of cloth. Because there might be variability from one bolt to another, the chemist decides to use a randomized block design, with the bolts of cloth considered as blocks. She selects five bolts and applies all four chemicals in random order to each bolt. The resulting tensile strengths follow. (one-way ANOVA) Bolt Chemical 1 2 3 4 5 1 50 45 51 48 44 2 50 44 52 49 47 3 52 45 55 50 45 4 50 48 52 52 46 (a) Analyze the data from this experiment (use α = 0.05) and draw appropriate conclusions. (b) Use the Tukey's test with α = 0.05 to make comparisons between pairs of means. (c) Use the Fisher LSD method with α = 0.05 to make comparisons between pairs of means.

Have you ever been frustrated because you could not get a container of some sort to release the last bit of its contents? An article reported on an investigation of this issue for various consumer products. Suppose five 6.0 oz tubes of toothpaste of a particular brand are randomly selected and squeezed until no more toothpaste will come out. Then each tube is cut open and the amount remaining is weighed, resulting in the following data: 0.51, 0.63, 0.42, 0.5, 0.35. Does it appear that the true average amount left is less than 10% of the advertised net contents? USE SALT (a) Check the validity of any assumptions necessary for testing the appropriate hypotheses. O The sample was randomly selected and the normal probability plot is not acceptably nonlinear. The sample was selected to represent a range of results and the normal probability plot is not acceptably nonlinear. The sample was selected to represent a range of results and the normal probability plot is not acceptably linear. O…

College students and STDs: A recent report estimated that 25% of all college students in the United States have a sexually transmitted disease (STD). Due to the demographics of the community, the director of the campus health center believes that the proportion of students who have a STD is higher at his college. He tests H0: p = 0.25 versus Ha: p > 0.25. The campus health center staff select a random sample of 150 students and determine that 43 have been diagnosed with a STD. Conduct a hypothesis test to address the director’s hypothesis. Use a 5% significance level to make your decision. Use the applet to determine the P‑value. Click here to open the applet. Which of the following is an appropriate conclusion based on the results?  The data provides strong evidence that the proportion of students at his college who have a STD is more than 25%.  The data suggests that the proportion of students at his college who have a STD is 29%.  Of the students surveyed at his college, 29%…

Rothamsted Experimental Station (England) has studied wheat production since 1852. Each year many small plots of equal size but different soil/fertilizer conditions are planted with wheat. At the end of the growing season, the yield (in pounds) of the wheat on the plot is measured. Suppose for a random sample of years, one plot gave the following annual wheat production (in pounds):  3.81 2.97 5.19 3.40 3.05 2.40 4.35 3.00 4.89 5.23 3.37 4.00 3.84 5.42 5.09 5.03 For this plot, the sample variance is . Another random sample of years for a second plot gave the following annual wheat production (in pounds):  3.53 3.65 3.89 4.19 3.44 3.42 3.58 3.83 3.46 4.32 3.58 3.45 3.77 3.54 3.48 4.07 For this plot, the sample variance is . Test the claim using  that the population variance of annual wheat production for the first plot is larger than that for the second plot.  Find (or estimate) the P-value of the sample…

Random collections of nine different solutions of a calcium compound were given to two laboratories, A and B. Each laboratory measured the calcium content (in mmol per liter) and reported the results. The data are paired by calcium compound. Compound Lab A (x) Lab B (y) 1 2 3 4 7 9. 9.36 14.80 8.79 11.33 10.56 15.61 13.70 12.03 11.56 9.14 14.74 8.67 11.51 10.63 15.59 13.74 12.22 11.56 (a) Rank-order the data using 1 for the lowest calcium reading. Make a table of ranks to be used in a Spearman rank correlation test. Compound Lab A (x) Lab B (y) d = x – y d2 1 3 4 7 8 Ed? Compute the sample test statistic. (Round your answer to three decimal places.) II

A farmer wants to know whether or not the sizes of Christmas trees differ between two separate fields on opposite sides of the farm (different elevation). In order to test this, he plants a number of trees in each field and measures them all after 2.5 years of growth. He then takes a random sample from each field and this is what he found: Group 1: Higher Elevation, N=25, Mean=3.3 ft, S=0.55 ft Group 2: Lower Elevation, N=23, Mean= 3.1, S=0.45 ft   Please calculate the test statistic and pvalue. What can be concluded?  Support your answer. Please calculate the 95% confidence interval Interpret the interval. What can be concluded?  Support your answer.

Two major automobile manufacturers have produced compact cars with engines of the same size. We are interested in determining whether or not there is a significant difference in the mean MPG (miles per gallon) when testing for the fuel efficiency of these two brands of automobiles. A random sample of eight cars from each manufacturer is selected, and eight drivers are selected to drive each automobile for a specified distance. The following data (in miles per gallon) show the results of the test. Assume the population of differences is normally distributed. Driver Manufacturer A Manufacturer B 1 36 30 2 31 31 3 30 28 4 30 27 5 29 27 6 33 30 7 35 25 8 29 31 The test statistic is 2.316. At  ? = 0.10,  the null hypothesis   should be revised .should not be tested.     should be rejected. should not be rejected.

Is the following a null or an alternative hypothesis? Iced coffee tastes better than hot coffee.