Original practice · fully worked
Original variant: daily-compounded monthly rate from one observed loan balance
A loan starts a month at 10,000, receives a month-end payment of 900, and then has balance 9,150. Its nominal annual rate is shared by another loan that compounds daily using 365 days and twelve equal months. Calculate the second loan's effective monthly rate.
- A
0.43% - B
0.45% - C
0.48% - D
0.50% - E
0.53%
Answer and calculation
The observed interest is 50, implying 0.5% monthly and a 6% nominal annual rate. Compounding one 365th of 6% for 365/12 days gives effective monthly rate 0.5012%, choice D.
Setup
Setup
Recover the first loan's monthly interest from its balance change.
I=9150−10000+900=50 jA=50/10000=0.005 Model
Model
Annualize nominally and apply the daily rate for one equal month.
i(12)=12(0.005)=0.06 jB=(1+0.06/365)365/12−1 Compute
Compute
The daily-compounded monthly rate is 0.501211%.
jB=0.0050121079 Answer
Answer
The second loan's effective monthly rate is 0.5012%, selecting choice D.
jB≈0.5012%(D)