Final answer:
The number of employees in a bargaining unit varies and is not fixed to a specific number; it depends on various factors including the employer's size and industry type. A labour union can negotiate for higher wages on behalf of its members.
Step-by-step explanation:
The question regarding how many employees must be in a bargaining unit does not have a single, universally applicable answer, as it can vary by jurisdiction and by the rules of the National Labor Relations Board (NLRB) or an equivalent body in other countries. Generally, a bargaining unit is a group of employees with a clear and identifiable community of interest who are represented by a single labour union in collective bargaining. The specific number of employees that can constitute a bargaining unit is not fixed and can range from two employees to thousands, depending on the size of the employer and the type of industry.
Union negotiations play a crucial role in determining wages and working conditions for union members. In a scenario where all firms in an industry must negotiate with a single union, and no firm is allowed to hire nonunion labour, a labor union can use the threat of a strike to achieve higher wages for its members, compared to what the equilibrium wage in the labour market would be without union influence.