Suppose a certain species bird has an average weight of xˉ=3.55 grams. Based on previous studies, we can assume that the weights of these birds have a normal distribution with σ=0.29 grams. Find the sample size necessary for an 85% confidence level with a maximal error of estimate E=0.09 for the mean weights of the hummingbirds. 10 5 10 100 47