Original practice · fully worked
Original variant: perpetual maintenance grants with a fixed annual step
A district pays 10 at the end of year 1, 13 at the end of year 2, 16 at the end of year 3, and continues increasing by 3 each year forever. At 5% effective, find the present value.
- A
1,000 - B
1,200 - C
1,400 - D
1,600 - E
1,800
Answer and calculation
A level perpetuity of 10 plus a three-unit arithmetic increase has value 1,400, choice C.
Setup
Setup
Retain the first-payment level of ten and isolate the three-unit step that begins with the second payment.
PV=0.0510+3k=1∑∞(k−1)vk Model
Model
The step component has discounted value one over i squared for each unit of annual increase.
k=1∑∞(k−1)vk=i21 Compute
Compute
At 5%, the level layer is 200 and the growth layer is 1,200.
PV=200+0.0523=1400 Answer
Answer
Their sum is 1,400, which appears in choice C.
PV=1400(C)