Question 1Multiple choicePresent worth & annual worth analysis
A company is considering a machine that costs $50,000 now. It is expected to save $12,000 per year in labour, received at the end of each year for 6 years, after which the machine can be sold for a salvage value of $8,000. The company's minimum attractive rate of return (MARR) is 10% per year, compounded annually. What is the present worth of the investment?
- A.
$2,263
- B.
$6,779
- C.
$10,263
- D.
$30,000
Worked solution
Draw the cash flow diagram: a $50,000 outflow at time 0, six equal $12,000 inflows at the ends of years 1 to 6, and a single $8,000 inflow at the end of year 6 (at the same time as the last saving). Discount every cash flow to time 0 at 10%.
Compound interest factors at , :
Present worth:
(Carrying unrounded factors gives $6,779.) The present worth is positive, so the machine earns more than the 10% MARR and is acceptable. Equivalently, the annual worth is , about $1,557 per year.
The tempting answer $2,263 forgets the salvage value entirely, and $10,263 adds the $8,000 salvage at face value without discounting it six years; both are common slips. $30,000 ignores the time value of money altogether (72,000 + 8,000 − 50,000).
$6,779 (positive, so the machine is acceptable)