1 ) Suppose a certain species bird has an average weight of = 3.80 grams. Based on previous studies, we can assume that the weights of these birds have a normal distribution with = 0.37 grams. For a small group of 10 birds, find the margin of error for a 70% confidence interval for the average weights of these birds.

2) Suppose a certain species bird has an average weight of = 3.55 grams. Based on previous studies, we can assume that the weights of these birds have a normal distribution with = 0.29 grams. Find the sample size necessary for an 85% confidence level with a maximal error of estimate = 0.09 for the mean weights of the hummingbirds.