An analyst needs to estimate the mean length of time it takes workers from a department to come back from lunch each day. Find the minimum sample size needed if the analyst needs to be 90% confident...

An analyst needs to estimate the mean length of time it takes workers from a department to come back from lunch each day. Find the minimum sample size needed if the analyst needs to be 90% confident that the sample mean is off by, at most, two minutes. Assume that standard deviation is fourteen minutes. (Approximate the answer)