Average Molecular weight of gas mixture

A 100kg mass of a gas mixture has the following composition:

CH4 - 30 mol%
H2 - 10 mol%
N2 - 60 mol%

what is the average molecular weight of this gas mixture?

You will use the percentages and molar masses of each compound/diatomic molecule to find the average molecular weight.

CH4= 16g/mol
H2= 2g/mol
N2= 28g/mol

(.30 * 16) + (.1 * 2) + (.60 * 28) = 21.8g/mol (answer)