Allen's hummingbird (Selasphorus sasin) has been studied by zoologist Bill Alther. Suppose a small group of 12 Allen's hummingbirds has been under study in Arizona. The average weight for these birds is x = 3.15 grams. Based on previous studies, we can assume that the weights of Allen's hummingbirds have a normal distribution, with o = 0.24 gram. (a) Find an 80% confidence interval for the average weights of Allen's hummingbirds in the study region. What is the margin of error? (Round your answers to two decimal places.) lower limit upper limit margin of error (b) What conditions are necessary for your calculations? (Select all that apply.) O o is unknown O o is known O normal distribution of weights O uniform distribution of weights O n is large (c) Interpret your results in the context of this problem. O We are 20% confident that the true average weight of Allen's hummingbirds falls within this interval. O We are 80% confident that the true average weight of Allen's hummingbirds falls within this interval. The probability that this interval contains the true average weight of Allen's hummingbirds is 0.20. O The probability that this interval contains the true average weight of Allen's hummingbirds is 0.80. (d) Find the sample size necessary for an 80% confidence level with a maximal margin of error E = 0.12 for the mean weights of the hummingbirds. (Round up to the nearest whole number.) hummingbirds Need Help? Read It Watch It Master It 2. [-/1 Points] DETAILS BBBASICSTAT8 8.R.012.S. MY NOTES ASK YOUR TEACHER PRACTICE ANOTHER Sherds of clay vessels were put together to reconstruct rim diameters of the original ceramic vessels at the Wind Mountain archaeological site. A random sample of ceramic vessels gave the following rim diameters (in centimeters). 15.9 13.4 22.1 12.7 13.1 19.6 11.7 13.5 17.7 18.1 L USE SALT (a) Use a calculator with mean and sample standard deviation keys to find the sample mean x and sample standard deviation s. (Round your answers to four decimal places.) x = 15,8 cm s = 3,5 cm (b) Compute a 98% confidence interval for the population mean u of rim diameters for such ceramic vessels found at the Wind Mountain archaeological site. (Round your answers to one decimal place.) lower limit cm upper limit cm3. [-/4 Points] DETAILS WAS BBBASICSTAT8 8.2.013. MY NOTES ASK YOUR TEACHER PRACTICE ANOTHER The method of tree ring dating gave the following years A.D. for an archaeological excavation site. Assume that the population of x values has an approximately normal distribution. 1257 1187 1229 1201 1268 1316 1275 1317 1275 (a) Use a calculator with mean and standard deviation keys to find the sample mean year x and sample standard deviation s. (Round your answers to the nearest whole number.) X = A.D. S = yr (b) Find a 90% confidence interval for the mean of all tree ring dates from this archaeological site. (Round your answers to the nearest whole number.) lower limit A.D. upper limit A.D . 4. [1/1 Points] DETAILS PREVIOUS ANSWERS BBBASICSTAT8 8.2.008.S. MY NOTES ASK YOUR TEACHER Consider a 90% confidence interval for u. Assume o is not known. For which sample size, n = 10 or n = 20, is the confidence interval longer? LA USE SALT O neither O 20 10 Need Help? Read It 5. [-/1 Points] DETAILS BBBASICSTAT8 8.R.008. MY NOTES ASK YOUR TEACHER PRACTICE ANOTHER Anystate Auto Insurance Company took a random sample of 382 insurance claims paid out during a 1-year period. The average claim paid was $1535. Assume o = $256. Find a 0.90 confidence interval for the mean claim payment. (Round your answers to two decimal places.) lower limit $ upper limit $ Find a 0.99 confidence interval for the mean claim payment. (Round your answers to two decimal places.) lower limit upper limit Need Help? Read It