1) Listed below are the amounts of mercury (in parts per million, or ppm) found
ID: 3181726 • Letter: 1
Question
1) Listed below are the amounts of mercury (in parts per million, or ppm) found in tuna sushi sampled at different stores. The sample mean is 1.004 ppm and the sample standard deviation is 0.327 ppm. Use technology to construct a 90% confidence interval estimate of the mean amount of mercury in the population. 1.45 0.71 0.84 0.69 1.19 1.38 0.77 What is the confidence interval estimate of the mean amount of mercury in the population?
2)Listed below are measured amounts of lead (in micrograms per cubic meter, or mu g divided by m cubedg/m3)in the air. The EPA has established an air quality standard for lead of 1.5mu g divided by m cubedg/m3.The measurements shown below were recorded at a building on different days. Use the given values to construct a 95% confidence interval estimate of the mean amount of lead in the air. Is there anything about this data set suggesting that the confidence interval might not be very good? 5.40 1.00 0.31 0.84 0.74 0.90 What is the confidence interval for the population mean?
3)In a sample of seven cars, each car was tested for nitrogen-oxide emissions (in grams per mile) and the following results were obtained: 0.12,0.07, 0.18, 0.16, 0.17, 0.08, 0.18. Assuming that this sample is representative of the cars in use, construct a 98% confidence interval estimate of the mean amount of nitrogen-oxide emissions for all cars. If the EPA requires that nitrogen-oxide emissions be less than 0.165 g divided by mig/mi, can we safely conclude that this requirement is being met? What is the confidence interval estimate of the mean amount of nitrogen -oxide emissions for all cars?
4)Twelve different video games showing substance use were observed and the duration times of game play (in seconds) are listed below. The design of the study justifies the assumption that the sample can be treated as a simple random sample. Use the data to construct a 95% confidence interval estimate of mu,the mean duration of game play,.
4047
3884
3849
4020
4327
4810
4649
4040
5011
4832
4342
43124312
What is the confidence interval estimate of the population mean
mu?
5) An IQ test is designed so that the mean is 100 and the standard deviation is 16
for the population of normal adults. Find the sample size necessary to estimate the mean IQ score of statistics students such that it can be said with 99%
confidence that the sample mean is within 8 IQ points of the true mean. Assume that sigmaequals=16and determine the required sample size using technology. Then determine if this is a reasonable sample size for a real world calculation.The required sample size is?
6) Randomly selected students participated in an experiment to test their ability to determine when one minute (or sixty seconds) has passed. Forty students yielded a sample mean of 61.7seconds. Assuming thatsigmaequals=10.6seconds, construct and interpret a 90%confidence interval estimate of the population mean of all students. What is the 90%confidence interval for the population mean mu?
7)A study of the ages of motorcyclists killed in crashes involves the random selection of 159drivers with a mean of38.34 years. Assuming that
sigmaequals=11.4years, construct and interpret a 90% confidence interval estimate of the mean age of all motorcyclists killed in crashes.
What is the 90% confidence interval for the population mean mu?
9) Salaries of 50 college graduates who took a statistics course in college have a mean, of$ 63, 400. Assuming a standard deviation,
sigma, of $10,709 construct a 95% confidence interval for estimating the population meanmu.
4047
3884
3849
4020
4327
4810
4649
4040
5011
4832
4342
43124312
Explanation / Answer
1. Here n=7 so t table value for 90% CI at 6 df is 1.943
Hence Margin of Error=t*sd/sqrt9n)=1.943*0.327/sqrt(7)=0.240
So confidence interval = mean+/-E=1.004+/-0.240=(0.764,1.244)
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