Consider nitrogen gas, N2, at 27.7°C.

Question

What percentage of nitrogen molecules have a speed within 1.00 m/s of the most probable speed?

Answer 1

Try using these:
https://answers.yahoo.com/question/index?qid=20081123194116AA3FxdL

use that for the average speed and standard deviation.

Then he range is so narrow I would assume a normal distribution and use that average and standard deviation in the normal table rather than trying to integrate the Maxwell probability function or something:

http://davidmlane.com/hyperstat/z_table.html