A restaurant manager classifies customers as regular, occasional, or new, and finds that of all customers $50 \%, 40 \%$, and $10 \%$, respectively, fall into these categories. The manager found that wine was ordered by $70 \%$ of the regular customers, by $50 \%$ of the occasional customers, and by $30 \%$ of the new customers.
a. What is the probability that a randomly chosen customer orders wine?
b. If wine is ordered, what is the probability that the person ordering is a regular customer?
c. If wine is ordered, what is the probability that the person ordering is an occasional customer?