In a particular race, the best times (in seconds) for swimming the 100 freestyle were 44.51, 45.91, 46.18, 46.62, and 46.89; the best times for the 100 backstroke were 50.02, 50.22, 50.34, 51.36, 52.85. Assuming these to be representative samples of all of the top times for swimming the two events, use software to produce a 95% confidence interval for the difference between mean times for the two events (freestyle minus backstroke); report whether the interval contains zero, or only positive numbers, or only negative numbers, and tell what this suggests.