The speed of nitrogen molecules in the atmosphere (at 20? c) follows a normal distribution with a mean speed of 500 meters/second and a standard deviation of 50 meters/second. which conclusion does this information best support? a. 84% of the molecules have speeds between 450 meters/second and 550 meters/second. b. 68% of the molecules have speeds between 450 meters/second and 550 meters/second. c. 50% of the molecules have speeds between 450 meters/second and 550 meters/second. d. 34% of the molecules have speeds greater than 550 meters/second.