6;

6. A random sample of 30 words from Jane Austen's Pride and Prejudice had a mean length of 4.08 letters with a standard deviation of 2.40 letters. A random sample of 30 words from Henry James's What Maisie Knew had a mean length of 3.85 letters with a standard deviation of 2.26 letters. We wish to test the null hypothesis that the mean word length is the same in the two books. Our samples produced a 95% confidence interval for the true difference in mean word length of (-0.97, 1.43). Which of the following gives a correct conclu sion for the test? (a) Because the confidence interval includes 0, we have con- vincing evidence that the true difference in means is 0. (b) Because the center of the interval is 0.23, we have convincing evidence that the mean length of words in Pride and Prejudice is greater than the mean length of words in What Maisie Knew. (c) Because the confidence interval includes 0, we don't have convincing evidence that the mean word length in the two novels is different. (d) Because the confidence interval includes more posi- tive than negative values, we have convincing evidence that the mean length of words in Pride and Prejudice is greater than the mean length of words in What Maisie Knew