1. A new postsurgical treatment is being compared with a standard treatment. Seven subjects receive the new treatment, while seven others (the controls) receive the standard treatment. The recovery times, in days, are given below.
Treatment 12 13 15 17 19 20 21
Control 15 18 21 25 29 33 36
Find a 95% confidence interval for the reduction in mean recovery time for patients receiving the new treatment.
2. In a study of the rate at which the pesticide hexaconazole is absorbed through skin, skin specimens were exposed to 24 µg of hexaconazole. Four specimens were exposed for 30 minutes and four others were exposed for 60 minutes. The amounts (in µg) that were absorbed were
30 minutes: 3.1 3.3 3.4 3.0
60 minutes: 3.7 3.6 3.7 3.4
Find a 95% confidence interval for the mean amount absorbed in the time interval between 30 and 60 min- utes after exposure.