Problem 31E

Can the accidental transposition of two consecutive digits in an airline ticket identification number be detected using the check digit?

Periodicals are identified using an International Standard Serial Number (ISSN). An ISSN consists of two blocks of four digits. The last digit in the second block is a check digit. This check digit is determined by the congruence ≡ 3d1 + 4d2 + 5d3 + 6d4 + 7d5 + 8d6 + 9d7 (mod 11). When d8 = 10 (mod 11), we use the letter X to represent d8 in the code.

Chapter 5—Cost VolumeProfit Relationships Primary purpose – to estimate how profits are affected by the following five factors: 1. Selling prices 2. Sales volume 3. Unit variable costs 4. Total fixed costs 5. Mix of products sold. However, to simplify calculations, three assumptions are held: 1. Selling price is constant. The price of a product or service will not change as volume changes. 2. Costs are linear and can be accurately divided into variable and fixed elements. The variable element is constant per unit. The fixed element is constant in total over the entire relevant range. 3. In multiproduct companies, the mix of products sold remains constant. Contribution margin – the amount remaining from sales revenue after variable exp