For a certain nationwide standardized test there are two commonly used preparation products on the market: StudyFocus and Prepara. A researcher in the Education department at a nearby university wants to estimate the difference between the mean score on the test by users of StudyFocus and the mean score on the test by users of Prepara. The researcher obtains the scores on the test from a random sample of 16 users of StudyFocus and a random sample of 15 users of Prepara. (These samples are chosen independently.) These data are shown in the table. Scores StudyFocus 487, 342, 496, 375, 522, 552, 574, 399, 596, 423, 523, 439, 595, 461, 611, 468 Prepara 566, 503, 573, 562, 549, 536, 540, 595, 566, 517, 509, 522, 523, 555, 546 Send data to calculator Assume that the two populations of scores are approximately normally distributed. Let u, be the population mean score on the test by the users of StudyFocus. Let My be the population mean score on the test by the users of Prepara. Construct a 95% confidence interval for the difference , -H, . Then find the lower and upper limit of the 95% confidence interval. Carry your intermediate computations to three or more decimal places. Round your answers to two or more decimal places. (If necessary, consult a list of formulas. Lower limit: X Upper limit