This Exam FM sample reference tests Annuities and Perpetuities. The increasing stream begins immediately, so shifting the standard increasing annuity one period earlier gives value (1.05)² divided by 0.05² = 441, choice D.
How to solve this Annuities and Perpetuities question
Setup
Setup
Index the immediate payment of one at time zero and subsequent payments two, three, and so on.
X=k=0∑∞(k+1)vk
Model
Model
The generating function for this increasing geometric-weighted sequence is one divided by one minus v squared.
X=(1−v)21
Compute
Compute
Replace one minus v by i divided by one plus i.
X=i2(1+i)2=0.0521.052=441
Answer
Answer
The present value is 441, corresponding to choice D.
X=441(D)
Test the method on unseen problems
Financial Mathematics Practice Examination I
30 original Exam FM questions across the syllabus, to be worked in 150 timed minutes, with a full worked solution for each one. Written for Exam FM, not copied from the SOA set. One-time $39 PDF.
Original variant: interest rate inferred from an increasing perpetuity
A perpetuity-immediate pays 1 after one year, 2 after two years, and continues increasing by one each year. Its present value is 110. Determine the annual effective interest rate.
A 8.00%
B 9.00%
C 10.00%
D 11.00%
E 12.00%
Answer and calculation
The increasing perpetuity-immediate value is one plus i divided by i squared; setting it to 110 gives i = 10%, choice C.
Setup
Setup
Use the standard value of an increasing perpetuity whose first payment is in year one.
110=i21+i
Model
Model
Rearrange the value equation into a quadratic in the positive annual rate.
110i2−i−1=0
Compute
Compute
The positive root is 0.10; the other root is economically inadmissible.
i=2201+441=0.10
Answer
Answer
The annual effective rate is 10.00%, corresponding to choice C.