有一投资项目，开始需要100美元的费用，以后三年产生50美元，然后就失去生产能力。 a．若利率为10％。该项目的现值是多少？ b．若利率升至15％。答案将有什么变化？为什么？ Consider an investment project that costs$100 to get started and yields$50 for the next threeyears and then stops being productive． a．If the interest rate is 10 percent，what is the present value of the project？ b．How does your answer change if the interest rate rises to 15 percent？Why？