Allen'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 = 0.26 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.)