The speed of nitrogen molecules in the atmosphere (at 20ºC) 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.

B. 68% of the molecules have speeds between 450 meters/second and 550 meters/second.

Step-by-step explanation:

Since there is a standard deviation of 50 meters per second, and the mean speed is 500 meters per second, the speeds would range between 500 - 50 meters per second and 500 + 50 meters per second, which would be a range of 450 to 550 meters per second.

If you remember the Empirical Rule (68-95-99), things that are one standard deviation from the mean are within 68% of the data. Two standard deviations would include 95% of the data. Three standard deviations would include 99% of the data. Since this question just covers one standard deviation, 68% of the molecules have speeds between 450 meters per second and 550 meters per second.

Hope this helps!