Calculate the present value of the following cash flows, rounding to the nearest dollar: 

a. A single cash inflow of $12,000 in five years, discounted at a 12% rate of return. 

b. An annual receipt of $16,000 over the next 12 years, discounted at a 14% rate of return.

c. A single receipt of $15,000 at the end of Year 1 followed by a single receipt of $10,000 at the end of Year 3. The company has a 10% rate of return. 

d. An annual receipt of $8,000 for three years followed by a single receipt of $10,000 at the end of Year 4. The company has a 16% rate of return.