I am doing work on sampling distributions however I do not understand these questions or what I am supposed to do, if someone could clear it up for me it would be a BIG help!!

"The level of nitrogen oxide in the exhaust of a particular car model varies with mean .9 grams per mile and standard deviation .15 grams per mile. A company has 125 cars of this model in its fleet"

1. What is the approximate distribution of the mean NOX emission level x-bar for these cars??

Does this question even make sense? and if so can someone explain it??

I can kind of guess what to do, but I am not sure. What I did was .15/sqrt(125) and got .0134??

2. What is the level L such that the probability that x-bar is greater than L is only 0.01? Hint: This requires a backward normal calculation.

This question I cannot do if I do not understand the first one (so I been told).. Can someone explain what to do etc? Thanks for the help