An article in Neurology (1998, Vol. 50, pp. 1246€“1252) discussed that monozygotic twins share numerous physical, psychological, and pathological traits. The investigators measured an intelligence score of 10 pairs of twins, and the data follow:

(a) Is the assumption that the difference in score is normally distributed reasonable? Show results to support your answer.

(b) Find a 95% confidence interval on the difference in mean score. Is there any evidence that mean score depends on birth order?

(c) It is important to detect a mean difference in score of one point with a probability of at least 0.90. Was the use of 10 pairs an adequate sample size? If not, how many pairs should have been used?

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Pair Birth order: 1 Birth order: 2 5.73 1 6.08 5.80 6.22 3 7.99 8.42 4 7.44 6,84 6.43 5 6.48 7.99 8.76 6.32 6.32 8. 7.60 7.62 6.59 6.03 10 7.52 7.67