The Gross margin analysis presents the sales compared to the cost of sales in table and graph formats and can be used to perform a substantive analytical procedure to provide evidence over the occurrence and valuation of revenue as well as related costs of goods sold. Required: Analyze the gross margin for the dining sales revenue stream (note that there is no cost of sales for lodging). Set a reasonably precise expectation for the gross margin percentage by month and a threshold for differences that need to be investigated. Using the Gross margin analysis, establish the relationship between the revenues and the cost of sales for the different months and compare this with your expectation. Assuming that the acceptable difference between the recorded amount and expected value for any given month is $5,000, are there any differences that don't match your expectations that require inquiry of PSU Hotel management?