1. A researcher hypothesizes that caffeine will increase the speed with which people read. To test this, the researcher randomly assigns 30 people into one of two groups: Caffeine (n1 = 15) or No Caffeine (n2 = 15). An hour after the treatment, the 30 participants in the study are asked to read from a book for 1 minute; the researcher counts the number of words each participant finished reading. The following are the resulting statistics for each sample: Caffeine (group 1) n1 = 15 M1 = 450 s1 = 35 No Caffeine (group 2) n2 = 15 M2 = 420 s2 = 30 Answer the following questions. a. Should you do a one-tailed test or a two-tailed test? Why? b. What is the research hypothesis? c. What is the null hypothesis? d. What is df1? What is df2? What is the total df for this problem? e. Assuming that the null hypothesis is true, what is the mean of the sampling distribution of the difference between independent sample means, 44/M1-M2)? f. What is the estimate of the standard error of the difference between independent sample means Sim1-M2)?