Lyme disease is spread in the northeastern United States by infected ticks. The ticks are infected mainly by feeding on mice, so more mice result in more infected ticks. The mouse population in turn rises and falls with the abundance of acorns, their favored food. Experimenters studied two similar forest areas in a year when the acorn crop failed. They added hundreds of thousands of acorns to one area to imitate an abundant acorn crop, while leaving the other area untouched. The next spring, 54 of the 72 mice trapped in the first area were in breeding condition, versus 10 of the 17 mice trapped in the second area. Estimate the difference between the proportions of mice ready to breed in good acorn years and bad acorn years. Let p1 and p2 be (respectively) the proportions of mice ready to breed in good acorn vears and t

Terrariums are self-contained ecosystems inside a closed container. A local farmer produces terrariums for sale, but must wait for the plants in the terrarium to grow before she can sell them.  On average, her terrariums take 30 days before they are ready to sell. She experiments with a new soil mixture, aiming to decrease the time it takes for the terrariums to be ready. In a sample of 12 terrariums with the new soil mixture, the farmer finds that the average time before they are ready is 21 days with a standard deviation of 3 days. in testing the hypotheses H0​:μ= 30 and Ha​:μ< 30, what is the value of the tt-test statistic? Round your answer to three decimal places.

A researcher's survey results indicate that about 50% of 12th graders consume less than 300g of vegetables at lunch, about 40% consume 300-600g, and only 10% of them consume more than 600g. A high school conducted a survey of student diets and health information, and reported data about 12th graders' vegetable intake at lunch is reported in the table photo.  If researchers wants to find out whether the high school has the same proportions of 12th graders in the vegetable intake categories as reported by the survey, what would the appropiate test statistic be to use and why. Choosing between an ANOVA, Chi -Square independence tests, Chi Square Goodness of Fit, and One sample proportion test?

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…

A quality control engineer studied the relationship between years of experience as a system control engineer and the capacity of the engineer to complete within a given time a complex control design including the debugging of all computer programs and control devices. A group of 25 engineers having widely differing amounts of experience (measured in months of experience) was given the same control design project. The results of the study are given in the following table with y 5 1 if the project was successfully completed in the allocated time and y 5 0 if the project was not successfully completed. a. Determine whether experience is associated with the probability of completing the task. b. Compute the probability of successfully completing the task for an engineer having

Rivers in North Carolina contain small concentrations of mercury that can accumulate in fish over their lifetimes. The concentration of mercury in fish tissue can be obtained by catching fish and sending samples to a lab for analysis. A study was conducted on fish from the Waccamaw and Lumber Rivers to investigate mercury levels in tissues of largemouth bass. At several stations along each river a group of fish were caught, weighed and measured; in addition a filet from each fish was sent to a lab so that the tissue concentration of mercury could be determined. In all, 171 fish were caught at 15 different research stations along the Waccamaw and Lumber Rivers. Data from fish caught at one of these stations is shown in the followinng table: length weight 1616 47.0 48.7 1862 2855 55.7 45.2 1199 1320 44.7 1225 43.8 870 38.5 1455 45.8 1220 44.0 1033 40.4 Compute the correlation between length and weight for these fish. (Assume the correlation conditions have been satisfied and round your…

Sarah believes that completely cutting caffeine out of a person's diet will allow him or her more restful sleep at night. In fact, she believes that, on average, adults will have more than two additional nights of restful sleep in a four-week period after removing caffeine from their diets. She randomly selects 8 adults to help her test this theory. Each person is asked to consume two caffeinated beverages per day for 28 days, and then cut back to no caffeinated beverages for the following 28 days. During each period, the participants record the numbers of nights of restful sleep that they had. The following table gives the results of the study. Test Sarah's claim at the 0.05 level of significance assuming that the population distribution of the paired differences is approximately normal. Let the period before removing caffeine be Population 1 and let the period after removing caffeine be Population 2. Numbers of Nights of Restful Sleep in a Four-Week Period With Caffeine 24 22 24 20…

Step 3: Assess the Evidence (Calculate the test statistic for the observed sample mean. Sketch the T-distribution and identify the position of the observed test statistic. Shade the area that represents the P-value. Use the test statistic to find the P-value.)

A medical study is conducted to determine which migraine treatment, A or B, provides faster relief. The study uses 10 volunteers who claim to suffer from migraines. Half of the volunteers are randomly assigned to use treatment A when they experience their first migraine. The other half are assigned to use treatment B. Then, after no treatment for one month, the treatments are reversed. The volunteers each record the amount of time it takes, in minutes, to experience relief from their migraine under each treatment. The data are displayed in the table. A 3-column table with 10 rows. Column 1 is labeled volunteer with entries 1, 2, 3, 4, 5, 6, 7, 8, 9, 10. Column 2 is labeled Treatment A with entries 10, 13, 13, 9, 13, 12, 14, 10, 8, 7. Column 3 is labeled Treatment B with entries 19, 18, 19, 15, 20, 16, 16, 16, 13, 17. A 99% confidence interval for the mean difference (A – B) in the time it takes to experience relief is –8.37 minutes to 0.732 minutes. Based on the confidence interval,…

5 Imagine that a company sells portable walkie-talkie radios to construction crews. The batteries for these radios last for an average of 55 hours. The purchasing manager for this company receives a brochure in the mail that advertises a new brand of batteries. This new brand of batteries is cheaper than the brand that the company currently uses. However, the purchasing manager is concerned that the cheaper batteries may have a shorter average battery life than the current brand. (Note: The number of hours that batteries last is called their battery life.) The pricing manager installs 40 randomly selected batteries of the cheaper brand in the company's walkie-talkie radios. He finds that the mean battery life for the sample is 52 hours, with a standard deviation of 10 hours. He wants to perform a statistical test at the 1% level of significance to determine whether the cheaper batteries have a shorter average battery life span than the average life span of the brand of batteries the…