Concept explainers
Salmonella in produce. Salmonella infection is the most common type of bacterial food-borne illness in the United States. How prevalent is salmonella in produce grown in the major agricultural region of Monterey, California? Researchers from the U S Department of Agnculture (USDA) conducted tests for salmonella in produce grown in the region and published their results in Applied and Environmental Microbiology (April 2011). In a sample of 252 cultures obtained from water used to Irrigate the region. 18 tested positive for salmonella In an independent sample of 476 cultures obtained from the region’s wildlife (e.g., birds), 20 tested positive for salmonella. Is this sufficient evidence for the USDA to state that the prevalence of salmonella in the region’s water differs from the prevalence of salmonella in the region’s wildlife? Use α = .01 to make your decision
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Statistics for Business and Economics (13th Edition)
- Cheek teeth of extinct primates. The characteristics of cheek teeth (e.g., molars) can provide anthropologists with information on the dietary habits of extinct mammals. The cheek teeth of an extinct primate species were the subject of research reported in the American Journal of Physical Anthropology (Vol. 142, 2010). A total of 18 cheek teeth extracted from skulls discovered in western Wyoming were analyzed. Researchers recorded the dentary depth of molars (in millimeters) for a sample of 18 cheek teeth extracted from skulls. These depth measurements are listed in the accompanying table. Anthropologists know that the mean dentary depth of molars in an extinct primate species— called Species A—is 15 millimeters. Is there evidence to indicate that the sample of 18 cheek teeth come from some other extinct primate species (i.e., some species other than Species A)? The data are given below (you will need to put it into a single column). You will need to calculate the sample…arrow_forwardCloud seeding, a process in which chemicals such as silver iodide and frozen carbon dioxide are introduced by aircraft into clouds to promote rainfall was widely used in the 20-th century. Recent research has questioned its effectiveness [Journal of Atmospheric Research (2010, Vol. 97 (2), pp. 513-525)]. An experiment was performed by randomly assigning 52 clouds to be seeded or not. The amount of rain generated was then measured in acre-feet. Here are the data for the unseeded and seeded clouds: Unseeded: 81.2 26.1 95.0 41.1 28.6 21.7 11.5 68.5 345.5 321.2 1202.6 1.0 4.9 163.0 372.4 244.3 47.3 87.0 26.3 24.4 830.1 4.9 36.6 147.8 17.3 29.0 Seeded: 274.7 302.8 242.5 255.0 17.5 115.3 31.4 703.4 334.1 430.0 1697.8 118.3 198.6 129.6 274.7 119.0 1656.0 7.7 40.6 92.4 200.7 32.7 4.1 978.0 489.1 2745.6 Construct a frequence distribution for the combined cloud-seeding rain measurements. Use 6 bins. Class Frequency -250 < x < 250 250 < x < 750 750 < x < 1250 1250 < x < 1750 1750 < x < 2250 2250…arrow_forwardAccording to the article “Rubbing Hands Together Under Warm Air Dryers Can Counteract Bacteria Reduction” (Infectious Disease News, September 22, 2010) washing your hands isn’t enough—good “hand hygiene” also includes drying hands thoroughly. The article described an experiment to compare bacteria reduction for three different hand-drying methods. In this experiment, subjects handled uncooked chicken for 45 seconds, then washed their hands with a single squirt of soap for 60 seconds, and then used one of the three hand-drying methods. After completely drying their hands, the bacteria count on their hands was measured. Suppose you want to carry out a similar experiment and that you have 30 subjects who are willing to participate. Describe a method for randomly assigning each of the 30 subjects to one of the hand drying methods (Select all that apply) 1)Choose two treatments and sort the subjects by gender. Then assign the men to one treatment and the woment to another treatment.…arrow_forward
- The Specific Absorption Rate (SAR) for a cell phone measures the amount of radio frequency (RF) energy absorbed by the user’s body when using the handset. Every cell phone emits RF energy. Different phone models have different SAR measures. To receive certification from the Federal Communications Commission (FCC) for sale in the United States, the SAR level for a cell phone must be no more than 1.6 watts per kilogram. A random sample of 20 of the highest SAR level for a random selection of cell phone models as measured by the FCC was collected. Find a 96% confidence interval for the true (population) mean of the Specific Absorption Rates (SARs) for cell phones. Assume that the population standard deviation is σ = 0.337 and the sample mean is 1.024arrow_forwardOne variety of corn is genetically modified to produce chemicals for defense against predators. The standard corn contains the same standard genotype, but without genetic modification for the chemicals. The two types of corn are then planted in randomly placed adjacent plots across a single field. The amount of predators that are present when the corn has matured are then recorded. The data that was recorded of the predators present among each type are listed. Has genetic alterations decreased the amount of predators for the altered genotype? Normality tests for the populations of both contain a p value less than 0.05. The given alpha is 0.05 Modified Corn (20, 18, 26, 23, 17, 23, 22) Standard Corn (89, 64, 102, 96, 56, 77, 84, 59) use an F test to determine if the variance between the 2 lists are different. Based on this result, state the correct 2 sample parametric test to be used. State the null and alternative. Show calculations while rounding to two decimal points.What is the…arrow_forwardFIV (feline immunodeficiency virus) attacks a cat's immune system causing FAIDS (feline acquired immunodeficiency syndrome). It is estimated that between 2 and 25 percent of the global domestic cat population is infected with the virus. FIV is primarily transmitted from cat to cat through biting. A one-step immunochromatographic (IC) test has been developed for the detection of FIV antibodies. It is estimated that 94.7% of cats with FIV test positive and 96.1% of cats without FIV test negative using this test. Assume that 5% of the local cat population is actually infected with FIV. Use this information to answer the following: (a) For a population of 100 000 cats: (i) how many are estimated to be infected with FIV? (ii) how many of the cats in (a)(i) will test positive? (b) Use your answers from (a) to help construct a 2 × 2 table of counts displaying the results for this sample. Complete the table. Estimate the proportion of local cats that would test negative for FIV but actually be…arrow_forward
- FIV (feline immunodeficiency virus) attacks a cat's immune system causing FAIDS (feline acquired immunodeficiency syndrome). It is estimated that between 2 and 25 percent of the global domestic cat population is infected with the virus. FIV is primarily transmitted from cat to cat through biting. A one-step immunochromatographic (IC) test has been developed for the detection of FIV antibodies. It is estimated that 94.7% of cats with FIV test positive and 96.1% of cats without FIV test negative using this test. Assume that 5% of the local cat population is actually infected with FIV.Use this information to answer the following: (a) For a population of 100 000 cats:i. how many are estimated to be infected with FIV?ii. how many of the cats in (a)(i) will test positive? (b) Use your answers from (a) to help construct a 2 x 2 table of counts displaying the results for this sample. Complete the table. (c) Estimate the proportion of local cats that would test negative for FIV but…arrow_forwardContamination of various food products is an ongoingproblem all over the world. The article “Prevalence andQuantitative Detection of Salmonella in Retail RawChicken in Shaanxi, China” (J. of Food Production,2013) reported the following data on the occurrence ofsalmonella in chicken of three different types: (1) supermarketchilled, (2) supermarket frozen, and (3) wetmarket fresh slaughtered.Sample Size# SalmonellaPositive Samples1. 60 27Type 2. 60 323. 120 45Does it appear that the incidence rate of salmonellaoccurrence depends on the type of chicken? State andtest the appropriate hypotheses using a significance levelof .05.arrow_forwardThe effects of heat stresses on the heat shield of the Crew Dragon spacecraft during re-entry was performed using complex computer programs that mimic actual flight using data gathered during the Apollo space program. What kind of study is this? -experimental -census -simulation -observationalarrow_forward
- Demarion Santana is interested in studying the growth rates of capsicum annuum (pepper) plants under bridges in California. He randomly selects 50 bridges in California and records the frequency, height, and number of peppers on any plants growing under these bridges. His results were published in the Almanac of Questionable Statistics, Vol 1 (2016). What is the population in this study? 1. Readers of the Almanac of Questionable Statistics 2. Capsicum annuum plants growing under the 50 bridges randomly selected to be included in the study 3. All capsicum annuum plants growing anywhere in California 4. All capsicum annuum plants growing under bridges in Californiaarrow_forwardVitamin D is important for maintaining strong bones by helping the body absorb calcium from food and sup-plements. The recommended amount of vitamin D is 400 IU (international units) per day. Many people take vitamin D supplements, often at levels greatly exceeding the recommended daily amount. What is the effect of taking too much vitamin D? Researchers investigated this in a double-blind randomized clinical trial. Subjects were divided into three groups. One, consisting of 109 subjects, took 400 IU per day for three years. second group, consisting of 100 subjects, took 4,000 IU per day for three years. A third group, consisting of 102 subjects, took 10,000 IU per day for three years. The total volumetric bone mass density of the tibia (the large bone located in the lower front portion of the leg, sometimes referred to as the shinbone) was measured in order to assess the effect of the different dosages of Vitamin D.11 The degrees of freedom for the ANOVA F statistic comparing the mean…arrow_forwardVermont maple sugar producers sponsored a testing program to determine the benefit of a potential new fertilizer regimen. A random sample of 27 maple trees in Vermont were chosen and treated with one of three levels of fertilizer suggested by the chemical producer. In this experimental setup, nine trees (three in each of three climatic zones) were treated with each fertilizer level and the amount of sap produced (in mL) by the trees in the subsequent season was measured. The results are presented in the following table. Southern Zone Central Zone Northern Zone 76.2 80.4 74.2 79.4 87.9 86.9 84.5 85.2 80.1 Low fertilizer Medium 87.0 95.1 93.0 98.2 94.7 96.2 88.4 90.4 922 fertilizer High 84.2 87.5 83.1 90.3 89.9 93.2 81.4 84.7 82.2 fertilizer Estimate the main effects of fertilizer levels and climatic zone, and their interactions. b. Construct an ANOVA table. You may give ranges for the P-values. Test the hypothesis that there is no interaction between fertilizer levels and climatic zone.…arrow_forward
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