From a random sample of 6 students in an introductory finance class that uses group-learning techniques, the mean examination score was found to be 79.78 and the sample standard deviation was 2.7.
For an independent random sample of 9 students in another introductory finance class that does not use group-learning techniques, the sample mean and standard deviation of exam scores were 73.54 and 8.6, respectively. Estimate with 99%
confidence the difference between the two population mean scores; do not assume equal population variances.
The 99% confidence interval is from a lower limit of to an upper limit of .
(Round to two decimal places as needed.)