Understanding Basic Statistics 6th Edition by Charles Henry Brase,Corrinne Pellillo Brase

تمرين 67

Zoology : Hummingbirds Allen's hummingbird ( selasphorus sasin ) has been studied by zoologist Bill Alther (Reference: Hummingbirds by K. Long and w. Alther). A small group of 15 Allen's hummingbirds has been under study in Arizona. The average wait for these birds is
= 3.15 grams. Based on previous studies, we can assume that the weights of Allen's hummingbirds have a normal distribution, with = 0.33 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
(b) What conditions are necessary for your calculations
(c) Interpret your results in the context of this problem.
(d) Sample Size Find the sample size necessary for an 80% confidence level with a maximal margin of error E = 0.08 for the mean weights of the hummingbirds.