Final answer:
The profit margin (Net income before taxes/net sales) is least helpful for an auditor assessing financial difficulties, as it doesn't directly indicate the entity's solvency or liquidity.
Step-by-step explanation:
The ratio that is least likely to assist an auditor in determining whether the entity is experiencing financial difficulties is Net income before taxes/net sales. This ratio, commonly known as the profit margin, tells us how much profit a company makes for every dollar of sales, but it does not directly reflect the company's ability to sustain its operations or meet its liabilities. In contrast, the ratios of net worth/total liabilities, cash/total assets, and total liabilities/total assets give more direct insights into a company's solvency and liquidity, which are critical when assessing financial health.