The article “Toward a Lifespan Metric of Reading Fluency” (S. Wallot and G. Van Orden, International Journal of Bifurcation and Chaos, 2011:1173–1192) described a study of reading speed for undergraduate and graduate students. In a sample of 24 undergraduates, the mean time to read a certain passage was 4.8 seconds, with a standard deviation of 1.9 seconds. In a sample of 24 Ph.D. students, the mean time was 2.8 seconds, with a standard deviation of 1.0 seconds. Find a 95% confidence interval for the difference in reading speed between the two groups.