could you please solve these and show me how to solve them

and here is the book these from ch 8,13,4,6,12

http://book.ivo-welch.info/ed3/toc.html

12. The roll of a fair coin pays off either +S50 or-$30. What is the risk and reward of an investment" in this bet? (3 points) A. S20, 40% B. S40, 40% C. $10, 4000 D. S25, 2000 E. $15, 1500 13. Which of the following statements is CORRECI? (4 points) A. If the cost of capital declines, this lowers a project's NPV. A. If the cost of capital declines, this lowers a B. The NPV method is regarded by most academics as being the best indicator of a project's profitability; hence, most academics recommend that firms use only this one method C. A project's NPV depends on the total amount of cash flows the project produces, but because the cash flows are discounted at the cost of capital, it does not matter if the cash flows occur early or late in the project's life. D. The NPV and IRR methods may give different recommendations regarding which of two mutually exclusive projects should be accepted, but they always give the same recommendation regarding the acceptability of a normal, independent project. 14. Does maintaining an equal-weighted or value-weighted portfolio take more trading effort? (3 points A. Equal-weighted B. Value-weighted C. About the same D. It depends on the specific portfolio E. None of the above