The concentration of carbon dioxide (CO2) in the atmosphere is increasing rapidly due to our use of fossil fuels. Because plants use CO2 to fuel photosynthesis, more CO2 may cause trees and other plants to grow faster. An elaborate apparatus allows researchers to pipe extra CO2 to a 30-meter circle of forest. They selected two nearby circles in each of three parts of a pine forest and randomly chose one of each pair to receive extra CO2. The response variable is the mean increase in base area for 30 to 40 trees in a circle during a growing season. We measure this in percent increase per year. Here are one year's data. Pair Control plot Treated plot Treated - Control 9.782 10.647 0.865 2 7.283 9.254 1.971 3 5.712 8.695 2.983 (a) State the null and alternative hypotheses. (Where u is the mean difference, treated minus control.) Но: и На: и ? : Explain clearly why the investigators used a one-sided alternative. The researchers have no preconceived idea what extra CO2 will do to the growth rate. The researchers have reason to believe that CO2 will decrease growth rate. The researchers have reason to believe that CO, will increase growth rate. (b) Carry out a test and report your conclusion in simple language. (Use a = 0.05. Round your answer to two decimal places.) t =

A gardener applied chemical "Z" to plants in a flower bed. (S)he observed that the plants grew dramatically during the next two weeks. Using only the information from the previous two sentences, write a hypothesis about the effect of chemical "Z" on plants. (Note: Your hypothesis must be a testable statement.) A researcher conducted a series of experiments to test the effect of chemical “Z” on plants. The data from the experiments is summarized in the graph below. (Image of the Graph attached.) Interpret the graph above. What did the researcher learn about the effect of chemical “Z?” Based on the researcher’s graph, what can you conclude about the hypothesis you wrote for Question 7 above?

In North America, between 100 million and 1 billion birds die each year by crashing into windows on buildings, more than any other human-related cause. This figure represents up to 5% of all birds in the area. One possible solution is to construct windows angled downward slightly, so that they reflect the ground rather than an image of the sky to a flying bird. An experiment by Klem et al. (2004) compared the number of birds that died as a result of vertical windows, windows angled 20 degrees off vertical, and windows angled 40 degrees off vertical. The angles were randomly assigned with equal probability to six windows and changed daily; assume for this exercise that windows and window locations were identical in every respect except angle. Over the course of the experiment, 30 birds were killed by windows in the vertical orientation, 15 were killed by windows set at 20 degrees off vertical, and 8 were killed by windows set at 40 degrees off vertical. . Clearly state an appropriate…

To illustrate the effects of driving under the influence (DUI) of alcohol, a police officer brought a DUI simulator to a local high school. Student reaction time in an emergency was measured with unimpaired vision and also while wearing a pair of special goggles to simulate the effects of alcohol on vision. For a random sample of nine teenagers, the time (in seconds) required to bring the vehicle to a stop from a speed of 60 miles per hour was recorded. Complete parts (a) and (b). Note: A normal probability plot and boxplot of the data indicate that the differences are approximately normally distributed with no outliers. Click the icon to view the data table. (a) Whether the student had unimpaired vision or wore goggles first was randomly selected. Why is this a good idea in designing the experiment? A. This is a good idea in designing the experiment because it controls for any "learning" that may occur in using the simulator. B. This is a good idea in designing the experiment because…