This is a fairly straightforward problem of its type. If this is for a course you are taking, then you should certainly have some idea what to do.
In order to help you most effectively, we'll need to see what you have learned, what you have tried, and where you got stuck. As it is, I don't know where to start.
Possibly you do know about the normal distribution, but are just confused as to whether the question is about a sample of 500, or something else. If so, the problem is not as complicated as you might think. Work on (a) first, ignoring the 500. If I were editing the problem, I would have said explicitly, "Calculate the probability that the volume of a given can is less than 1025 ml."