Suppose a certain species bird had an average weight of x=3.55grams. based on the previous studies we can assume that the weight of these birds have...

Suppose a certain species bird had an average weight of x=3.55grams. based on the previous studies we can assume that the weight of these birds have a normal distribution with o=0.29grams. find the sample size necessary for an 85% confidence level with a maximum error of estimated E=0 .09 for the mean weights of the hummingbirds