Final answer:
The young men on the train silence Mrs. Schächter to end the disturbance caused by her screams and possibly to quell a terror that they all internally feel.
Step-by-step explanation:
The young men on the train bind, gag, and beat Mrs. Schächter because they cannot endure her fearful screaming, which disturbs the oppressive and tense environment of the train carriage. Additionally, her vocal expressions of terror might reflect the internalized fears of the passengers, adding to the sense of desperation and discomfort among them. Although not explicitly stated in these excerpts, such actions typically arise out of a combination of the desire to silence a disturbing element and a shared fear of facing the terrible reality that they might all be trying to suppress.