llen's hummingbird (Selasphorus sasin) has been studied by zoologist Bill Alther.† Suppose a small group of 10 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 σ = 0.28 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.) uniform distribution of weightsnormal distribution of weightsσ is unknownσ is knownn is large

A researcher constructs a confidence interval using the value z*=1.44. What confidence level does their interval have

A sample of 49 sudden infant death syndrome (SIDS) cases had a mean birth weight of 2998 g. Based on other births in the county, we will assume σ = 800 g. Calculate the 95% confidence interval for the mean birth weight of SIDS cases in the county. Interpret your results.

A sample of 20 cows is drawn to estimate the mean weight of a large herd of cattle.  If the standard deviation of the sample is 96 kg, what is the margin of error in a 90% confidence interval estimate?

8.2  Question 3).  According to the February 2008 Federal Trade Commission report on consumer fraud and identity theft, Arkansas had 1,601 complaints of identity theft out of 3,482 consumer complaints ("Consumer fraud and," 2008). Calculate a 90% confidence interval for the proportion of identity theft in Arkansas.

A study of 22 goats reveals that the average length of a goat’s tail is 6.3 inches. If the standarddeviation is known to be 1.2 inches find a 95% confidence interval for the mean tail length.

Question 6 Is smoking during pregnancy associated with premature births? To investigate this question, researchers selected a random sample of 118 pregnant women who were smokers. The average pregnancy length for this sample of smokers was 255 days. From a large body of research, it is known that length of human pregnancy has a standard deviation of 16 days. The researchers assume that smoking does not affect the variability in pregnancy length. Find the 95% confidence interval to estimate the length of pregnancy for women who smoke. (Note: The critical z-value to use, Ze, is: 1.960) ) Your answer should be rounded to 3 decimal places.