a) C_O is the initial cash flow on an investment, and C_I is the cash flow at the end of one year

The symbol r is the discount rate.

i)Is C_O usually positive or negative?

ii)What is the formula for the Present Value (PV) of an investment?

iii)What is the formula for the Net Present Value (NPV)?

iv)The symbol r is often termed OPPORTUNITY COST OF CAPITAL, Why?

v)If the investment is risk-free, what is the appropriate measure of r?