please answer both!

a 4. You go to your desk and your boss comes in. I need you to do some work for me. Read this and tell me what you think. The assignment indicates that following StuartCo Trains is a large Tank maker. It recently built the T123. It can carry a huge payload and is more nimble than other tanks. Initial project investments were $13B. Assume that the initial investment was paid on Dec 31, 2010. Assume that StuartCo will produce 60 Tanks per year for five years. Each Tank will be sold for $230M and total operating costs are 75% of revenues. Assume that revenues and costs occur at year-end with the first revenues (and costs) occurring on Dec 31, 2011. The assignment your boss gives you asks you to determine the NPV of the project if StuartCo's cost of capital is 11%? Calculate the NPV as of Dec 31, 2010. Ignore taxes and assume that there are no terminal year cash flows. Show your work, as appropriate and clearly state your answer (5 points) 5. Your boss then asks what is the payback period for the StuartCo investment outlined above? Amd, the CEO doesn't really get payback so how should I explain it to him. What does the payback period calculation mean