Final answer:
An author might include unproven rumors in a story to create mystery, reveal character traits, or explore societal themes related to the elderly and the supernatural.
Step-by-step explanation:
An author might include a rumor about an old woman being a fortune teller in a story without providing proof to create a sense of mystery, suspense or to illustrate a theme. By doing so, the author taps into the reader's imagination, inviting them to question reality versus hearsay, truth versus superstition, and draws them deeper into the narrative. It could also be a device to reveal character traits or social beliefs, such as the fear or respect of the elderly and the supernatural.
Moreover, the use of the fortune teller trope allows the author to explore cultural attitudes towards magic and elderly women, which can be historically complex and varied. As such, the rumor of fortune telling might serve to characterize the old woman in question, or offer commentary on societal treatment of the elderly or belief in the occult.