Problem-Solving Ability Two groups of students are given a problem-solving test, and the results are com- pared. Find the 90% confidence interval of the true difference in means. Mathematics majors Computer science majors X = 83.6 = 4.3 n = 36 X = 79.2 02=3.8 11 = 36 Literacy Scores Adults aged 16 or older were assessed in three types of literacy in 2003: prose, document, and quantitative. The scores in document literacy were the same for 19- to 24-year-olds and for 40- to 49-year-olds. A random sample of scores from a later year showed the following statistics. Age group 19-24 40-49 Mean score 280 315 Population standard deviation 56.2 52.1 Sample size 40 35 Construct a 95% confidence interval for the true difference in mean scores for these two groups. What does your interval say about the claim that there is no difference in mean scores? Battery Voltage Two brands of batteries are tested, and their voltage is compared. The data follow. Find the 95% confidence interval of the true difference in the means. Assume that both variables are normally distributed. Brand X Brand Y X=9.2 volts X = 8.8 volts = 0.3 volt " = 27 = 0.1 volt 11 = 30