A woman joins a package shipping firm as a truck driver. she is required to join the labor union six weeks after she starts work, and she must remain a member. what type of union arrangement exists at the firm?

In this situation she would have a compulsory union membership as part of the bargaining agreement between the union and the company. This would be to protect the union membership so that they have more power to push for demands by having more members and also so that when they gain new demands, their membership can benefit from it since they have been won by the support of all the members.