The jetliner is traveling against the wind. The net speed of the jetliner is 590 mph - 36 mph = 554 mph The time it takes for the jetliner to arrive at the destination is 1850 miles / 554 mph = 3.34 hours
It increases confidence because the more times you conduct the same experiment over and over should either prove your hypothesis right and wrong and eliminate any random occurrences that might affect your results.
