"Self-Report of Cochlear Implant Use and Satisfaction by Prelingually Deafened Adults," published in Ear & Hearing in June 1996, evaluated noise and voice recognition, with use of a hearing aid, by 12 adults who had been deaf all their lives.

a. Construct a stemplot of the data to verify that the shape is roughly normal.

b. One of these is a 90% and the other a 95% confidence interval for population mean recognition score: (53.27, 72.90) and (55.07, 71.09). Which one is the 90% interval?

c. The scores have mean 63 and standard deviation 15. If a patient just guessed at answers on the hearing test, he or she would be expected to score only 50. To get an idea of how much higher 63 is than 50 in this situation, standardize to .

d. For t distributions with 11 degrees of freedom, the probability of being greater than 2.72 is 0.01. Is a score of 63 significantly higher than 50?

e. The null hypothesis states that m 50. What does the alternative state?

f. One year after these 12 patients received cochlear implants, they were tested again on noise and voice recognition. Is this a paired, two-sample, or several-sample design?