The National Assessment of Educational Progress (NAEP) includes a mathematics test for eigth-grade students. Scores on the test range from 0 to 500. Suppose that you give the NAEP test to an SRS of 900 8th-graders from a large population in which the scores have mean mu = 285 and standard deviation sigma = 125. The mean x-bar will vary if you take repeated samples. Suppose that we took an SRS of 1600 8th-graders and found x-bar =288. Compared with an SRS of 900 8th-graders, the margin of error for a 95% confidence interval for mu is