3. As a shareholder of a firm that is contemplating a new project, would you be more concerned with the accounting break-even point, the cash break-even point, or the financial break-even point? Why?

From the shareholder perspective, the financial break-even point is the most important. A project can exceed the accounting and cash break-even points but still be below the financial break-even point. This causes a reduction in shareholder (your) wealth.
4. In an effort to capture the large jet market, Airbus invested $13 billion developing its A380, which is capable of carrying 800 passengers. The plane has a list price of $280 million. In discussing the plane, Airbus stated that the company would break even when 249 A380s were sold.
a. Assuming the break-even sales figure given is the cash flow break-even, what is the cash flow per plane?
The cash flow per plane is the initial cost divided by the breakeven number of planes, or:
Cash flow per plane = $13,000,000,000 / 249
Cash flow per plane = $52,208,835

b. Airbus promised its shareholders a 20 percent rate of return on the investment. If sales of the plane continue in perpetuity, how many planes must the company sell per year to deliver on this promise?
In this case the cash flows are a perpetuity. Since we know the cash flow per plane, we need to determine the annual cash flow necessary to deliver a 20 percent return. Using the perpetuity equation, we find:
PV = C /R
$13,000,000,000 = C / .20
C = $2,600,000,000

This is the total cash flow, so the number of planes that must be sold is the total cash flow divided by the cash flow per plane, or:
Number of planes = $2,600,000,000 / $52,208,835
Number of planes = 49.80 or about 50 planes per year

c. Suppose instead that the sales of the A380 last for only 10 years. How many planes must Airbus sell per year to deliver the same rate of return?