Weight Loss X runs a number of weight reduction centers within a large city. From the historical data it was found that the weight of the participants is normally distributed with a mean of 160 lbs and a standard deviation of 30 lbs. Calculate the standard error of the average sample weight when 20 participants are randomly selected for the sample? Calculate the probability that the average sample weight is greater than 170 lbs when 20 participants are randomly selected for the sample?