# Confidence Intervals for the Mean1.Assume that a sample is use.docx

15 de Nov de 2022

### Confidence Intervals for the Mean1.Assume that a sample is use.docx

• 1. Confidence Intervals for the Mean 1.Assume that a sample is used to estimate a population mean μμ. Find the margin of error M.E. that corresponds to a sample of size 11 with a mean of 30.3 and a standard deviation of 13.8 at a confidence level of 99.5%. Report ME accurate to one decimal place because the sample statistics are presented with this accuracy. M.E. = Answer should be obtained without any preliminary rounding. However, the critical value may be rounded to 3 decimal places. 2.The effectiveness of a blood-pressure drug is being investigated. An experimenter finds that, on average, the reduction in systolic blood pressure is 19.8 for a sample of size 906 and standard deviation 19.6. Estimate how much the drug will lower a typical patient's systolic blood pressure (using a 95% confidence level). Enter your answer as a tri-linear inequality accurate to one decimal place (because the sample statistics are reported accurate to one decimal place). < μ < Answer should be obtained without any preliminary rounding. 3.You must estimate the mean temperature (in degrees Fahrenheit) with the following sample temperatures:
• 2. 62.3 39.4 56.7 57.7 63.5 65.5 53.9 67.7 63.1 56.5 61.7 59.7 Find the 98% confidence interval. Enter your answer as an open-interval (i.e., parentheses) accurate to two decimal places (because the sample data are reported accurate to one decimal place). 98% C.I. = Answer should be obtained without any preliminary rounding. 4.SAT scores are distributed with a mean of 1,500 and a standard deviation of 300. You are interested in estimating the average SAT score of first year students at your college. If you would like to limit the margin of error of your 95% confidence interval to 25 points, how many students should you sample? Make sure to give a whole number answer. 5.For a confidence level of 99% with a sample size of 21, find the critical t value. For Question #5 when you are asked to use find the t-value corresponding to a certain confidence level and degrees of
• 3. freedom use this link: http://www.usablestats.com/calcs/tinv Remember that we are only calculating Confidence Intervals using t! 6.If n=26, ¯xx¯(x-bar)=31, and s=4, find the margin of error at a 95% confidence level Give your answer to two decimal places. 7.Assume that a sample is used to estimate a population mean μμ. Find the margin of error M.E. that corresponds to a sample of size 13 with a mean of 64.5 and a standard deviation of 17.9 at a confidence level of 95%. Report ME accurate to one decimal place because the sample statistics are presented with this accuracy. M.E. = Answer should be obtained without any preliminary rounding. However, the critical value may be rounded to 3 decimal places. THIS LINKS MIGHT BE USEFUL: http://onlinestatbook.com/2/estimation/intro.html http://onlinestatbook.com/2/estimation/characteristics.html http://onlinestatbook.com/2/estimation/confidence.html http://onlinestatbook.com/2/estimation/mean.html http://onlinestatbook.com/2/estimation/t_distribution.html https://www.learner.org/courses/againstallodds/unitpages/unit26 .html https://www.youtube.com/watch?v=MuIir6rGNN0&feature=yout u.be