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# Problem #1 Finding a confidence interval for a population mean:

Problem #1Finding a confidence interval for a population mean: Part AA university survey 36 randomly selected students and asks the number of dollars spent on textbooks/supplies during the academic year. The results are (in dollars) shown below:28265393090284 822Use Excel to construct a 90% confidence interval for the mean dollars spent.Would a given mean value of $600 be likely, given the calculated confidence interval? Yes or No?Find Answer to: 90% confidence interval (_________+/-_____________)Problem #2Finding a T-based confidence interval for a population mean: Part BThe GPAs of 15 randomly sampled students are shown in the table below: Would a given mean GPA of 3.72 be likely given the calculated interval? Yes or No?Using Excel, construct a 95% confidence interval using a T-distribution for the mean GPA2.873.353.614.003.732.953.023.463.213.503.893.203.622.773.92Find Answer to: __________+/-_______________Problem #3Finding Tc for a proportion population: Part CIn a survey of 320 local high school students, 182 said they sent text on a daily basis.Using Excel construct an 80% confidence interval for the proportion of local high school students who send text daily. Would a proportion of 60% be likely, given the calculated confidence interval?Find Answer to: 80% confidence interval ________+/-___________Round to two decimal placesProblem #4In determining the sample size for a confidence interval for u-q knownPart DQuestion: A company wants to estimate the average sales lunch expense. They want to be within $5 of the true mean when using a confidence interval of 95%. The standard deviation is estimated at $25.How many lunch receipts must they sample?Round to whole number, if needed(Remember when calculating a sample size, we need to round UP to the next whole number, not the closest whole number if needed)If less than that many receipts are sampled, which answer best describes what happens?A) The error is more than the desired error of $5B)The error is less than the desired error of $5C)The level of confidence must be increasedD)The confidence interval must be widenedE)The standard deviation is not accurately estimated