Worked-out example Suppose your current plan is Mobily Postpaid 50 with 3 GB. You just paid SR57.5 (SR50 + VAT) for the current month's service but you realize that you need a lot more than 3 GB of data and you can't wait till the end of the month to switch. You are considering the following two plans. Which one will you get and why? Plan Mobily Mobily Marginal Marginal Postpaid 100 Postpaid 300 Benefit Cost Data 20 GB 150 GB 130 GB Price 1 15 SAR / 345 SAR / 230 SAR / month month month Total Cost 172.5 SAR 402.5 Worked-out example (continued) What role was played by the money you already paid for your current plan (SR57.5 for Postpaid 50)? Did it have an impact on your decision? Why or why not? That SR57.5 is know as sunk cost