Contaminated water: Polychlorinated biphenyls (PCBS) are a group of synthetic oil-like chemicals that were at one time widely used as insulation in electricalequipment and were discharged into rivers. They were discovered to be a health hazard and were banned in the 1970s. Assume that water samples are beingdrawn from a river in order to estimate the PCB concentration. Suppose that a random sample of size 65 has a sample mean of 1.95 parts per billion (ppb).Assume the population standard deviation is o=0.41 ppb.Part: 0 / 3Part 1 of 3(a) Construct a 98% confidence interval for the PCB concentration. Use tables or technology. Round your answers to at least two decimal places.OD-The confidence interval is

Answered: Image /qna-images/answer/11ee5c6a-1d4e-403d-8d5b-fa036342f551.jpg

Answered: equipment and were discharged into…

MATLAB: An Introduction with Applications

6th Edition

ISBN:9781119256830

Author:Amos Gilat

Publisher:Amos Gilat

Chapter1: Starting With Matlab

Section: Chapter Questions

Problem 1P

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6.20 Mean OC in young women. Refer to the previous exercise. A biomarker for bone formation measured in the same study was osteocalcin (OC), measured in the blood. For the 31 subjects in the study, the mean was 33.4 nanograms per milliliter (ng/ml). Assume that the standard deviation is known to be 19.6 ng/ml. Report the 95% confidence interval.
An education analyst believes that the average SAT scores for women exceed the average SAT scores for men in the United States. The analyst does not know the population standard deviation of SAT scores for men and women. The following information outlines the information for each sample: Women Men n1 = 10 n2 = 20 X1 = 1080 X2 = 1000 s1 = 100 s2 = 125 Assuming that the population variances are equal, test the analyst’s claim at the 0.05 level.
In a 5-year follow-up of bilateral stimulation of the subthalamic nucleus among 49 patients with advanced Parkinson's disease, investigators assessed changes in symptoms as measured by the Unified Parkinson's Disease Rating Scale (range= 0 to 108, with higher values denoting more symptoms). Assume this measure follows a normal distribution. The mean score at baseline was 55.7. The standard deviation of change from baseline to 5 years was 15.3. What minimum sample size would be needed to detect a mean change of 5 units with 80% power if a two-sided test is used with alpha=0.05?
An oceanographer claims that the mean dive duration of a North Atlantic right whale is 11.3 minutes. A random sample of 35 dive durations has a mean of 12.5 minutes and a standard deviation of 2.3 minutes. At α=0.01 is there enough evidence to reject the oceanographer's claim? Complete parts (a) through (d) . Assume the population is normally distributed. (a)Identify the claim and state H0 and Ha. (b) The claim is the ______ hypothesis (c) Decide whether to reject or fail to reject the null hypothesis. (d) Interpret the decision in the context of the original claim.
A research neurologist is testing the effect of a drug on response time by injecting 100 rats with a dose of a particular drug and then testing their response time. The mean response time for rats not injected is known to be equal to 1.2 seconds with a standard deviation of 0.5 seconds. A random sample of 100 rates is taken from the population. The mean response time for these 100 injected rats is 1.05 seconds. Using a = 0.01, a. Setup the null and alternate hypothesis b. Choose an appropriate test statistic, fill in the all of the information, and solve for the test statistic.
A survey conducted by the American Automobile Association (AAA) showed that a family of four spends an average of $215.60 per day while on vacation. Suppose a sample of 64 families of four vacationing at Niagara Falls resulted in a sample mean of $252.45 per day and a sample standard deviation of $74.50. a. Develop a 95% confidence interval estimate of the mean amount spent per day by a family of four visiting Niagara Falls (to 2 decimals). $ to $ b. Based on the confidence interval from part (a), does it appear that the population mean amount spent per day by families visiting Niagara Falls differs from the mean reported by the American Automobile Association? Explain. I. No. The lower limit for the confidence interval for the population mean at Niagara Falls is greater than overall average daily vacation expenditure of $215.60 per day. This suggests we cannot determine if the population mean at Niagara Falls is greater than the overall average daily vacation expenditure. II. Yes. The…
An oceanographer claims that the mean dive duration of a North Atlantic right whale is 11.7 minutes. A random sample of 35 dive durations has a mean of 12 4 minutes and a standard deviation of 22 minutes. At a=0.10 is there enough evidence to reject the oceanographer's claim? Complete parts (a) through (d) below. Assume the population is normally distributed (a) Identify the claim and state Ho and Ha Ho μ = 11.7 Ha H #11.7 (Type integers or decimals Do not round) The claim is the null hypothesis. (b) Use technology to find the P-value. Find the standardized test statistic, t t= (Round to two decimal places as needed.) Obtain the P-value P= (Round to three decimal places as needed.) (c) Decide whether to reject or fail to reject the null hypothesis. greater than a ▼ Ho because the P-value (d) Interpret the decision in the context of the original claim. There enough evidence at the (Type integers or decimals. Do not round) level of significance to CORE the claim that the mean dive…
A biology student measured the ear lengths of an SRS of 10 Mountain cottontail rabbits, and an SRS of 10 Holland lop rabbits. The ear lengths for the two samples are listed in the two tables attached (see attached image). (a) Calculate a 95% confidence interval for the difference in mean ear lengths between Mountain cottontail rabbits and Holland lop rabbits. Make sure to define which is “µ1” and which is “µ2.” (You can complete the calculations either by hand or using R, but remember to show all your work.) (b) Do Holland lop rabbits have longer ears on average than Mountain cottontail rabbits? Carry out a test of significance to answer this question. Show your work at each step. Don’t forget to state the hypotheses at the start (making sure to define all parameters), and to include a conclusion in terms of the original problem. (You can complete the calculations either by hand or using R, but remember to show all your work.)
A popular flashlight that uses two D-size batteries was selected, and several of the same models were purchased to test the "continuous-use life" of D batteries. As fresh batteries were installed, each flashlight was turned on and the time noted. When the flashlight no longer produced light, the time was again noted. The resulting "life" data from Rayovac batteries had a mean of 20.5 hours. Assume these values have a normal distribution with a standard deviation of 1.34 hours. (Give your answers correct to four decimal places.) (a) What is the probability that one randomly selected Rayovac battery will have a test life between 20 and 21.8 hours? x (b) What is the probability that a randomly selected sample of 6 Rayovac batteries will have a mean test life between 20 and 21.8 hours? x (c) What is the probability that a randomly selected sample of 13 Rayovac batteries will have a mean test life between 20 and 21.8 hours? x (d) What is the probability that a randomly selected sample of 64…
Dairy cows at large commercial farms often receive injections of bST (Bovine Somatotropin), a hormone used to spur milk production. Bauman et al. (Journal of Dairy Science, 1989) reported that 12 cows given bST produced an average of 28.0 kg/d of milk. Assume that the standard deviation of milk production is 2.25 kg/d.(a) Find a 99% confidence interval for the true mean milk production.(b) If the farms want the confidence interval to be no wider than ±1.25 kg/d, what level of confidence would they need to use?
A random sample of 75 eighth grade students scores on a national mathematics assessment test has a score o 272. This test result prompts a state school administrator to declare that the mean score for the state’s eighth graders of this exam is more than 270. Assume that the population standard deviation is 30, At a = 0.03, is there enough evidence to support the administrator’s claim? Compare parts (a) through (e).
A manufacturer claims that the average tensile strength of thread A exceeds the average tensile strength of thread B by at least 9 kilograms. Researchers wish to test this claim using a 0.05 level of significance. How large should the samples be if the power of the test is to be 0.9 when the true difference between thread types A and B is 6 kilograms? The population standard deviation for thread A is 6.24 kilograms and the population standard deviation for thread B is 5.61 kilograms.

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