Charles Yip Choy is a director in Aqua Ltd.Company. You are the Management Accountant.The company produces and sells luxury water beds. The most recent monthly sales results showed a decrease in sales of water beds for the 3rd consecutive month. At the same time production costs have increased in relation to the amount of units sold. You have been championing the cause for the implementation of a full system of Standard costing and Variance analysis. In a recent meeting with Charles you voiced your concern about the recent results and the need for a Standard costing system, as you believe that this would greatly assist in pointing to the cause(s) of the drop in sales units and the cost increases. Charles has some knowledge of such a system but wishes to learn a bit more, especially in relation to the investigation of variances. As Management Accountant, draft a reply to Charles which discusses the various factors to be considered in deciding when a variance should be investigated.