How does voice affect the credibility of a text?

Which is not among the style choices a writer would use, if he or she is trying to establish a formal writing style/

Read the excerpt below and answer the question. she was a small woman, short and straight-waisted like a child in her brown cotton gown. her forehead was mild and benevolent between the smooth curves of gray hair; there were meek downward lines about her nose and mouth; but her eyes, fixed upon the old man, looked as if the meekness had been the result of her own will, never of the will of another. in at least one hundred words, explain how this excerpt uses explicit and implicit details to describe sarah penn.

London includes a quote about john thornton as he is observing hal attempt to motivate the exhausted dogs "it was idle, he knew, to get between a fool and his folly". if the word "idle" is defined as "of no real worth, importance, or significance", what does this statement mean with regard to hal? who is the fool? what is hal's folly? why would john thornton think it of no real worth or useless to intervene?