Final answer:
The lowest acceptable transfer price for Division X in Case B is the variable cost of $12 per unit, provided that selling to Division Y does not limit external sales. If external sales are affected, the opportunity cost must be included, making the lowest transfer price $26.
Step-by-step explanation:
The lowest acceptable transfer price from the perspective of Division X in Case B, considering that there are no savings in variable selling costs on intra-company sales, would be the variable cost per unit plus any opportunity cost incurred by selling internally rather than externally. In this case, the variable cost per unit for Division X is $12. Since Division X is not at full capacity and is selling 71,000 units to outside customers (out of 91,000 capacity), it can produce the additional 20,000 units for Division Y without incurring additional fixed costs, which means the transfer price must cover just the variable cost of $12 per unit. However, if producing for Division Y would mean selling fewer units to the external market, then the opportunity cost would be the contribution margin on lost external sales (external price minus variable cost), which would have to be added to the transfer price. The selling price to outside customers is $26, so if selling internally affects external sales, the opportunity cost is $14 ($26 - $12) per unit, making the lowest transfer price $26.