Jack is a college athlete who has been weighing himself weekly on the same scale in the athletic center for the past few years. Jack’s mean weight over the last nine weeks is 180 lbs. Over a period of a few months, Jack’s weight measurements are approximately normal, with a standard deviation of about 3 lbs. Assume that 3 lbs is the true standard deviation in Jack’s weight. Suppose that Jack asks you to compute a 90% confidence interval for his true mean weight. First, identify the positive critical value, , for a 90% level of confidence using software or a table of critical values. Then, derive the standard error of the mean, SE. Finally, compute the margin of error, , for the 90% confidence interval for Jack’s mean weight. Please enter all values to three decimal places.