An article described a study of reading speed for undergraduate and graduate students. in a sample of 12 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. let μxμx represent the population mean for undergraduates and let μyμy represent the population mean for ph. d. students. find a 95% confidence interval for the difference μx−μyμx−μy. round down the degrees of freedom to the nearest integer and round the answers to three decimal places.