Question 1124448
18000 was invested when yumi was 10 years old.
the investment was for 7 years.
the interest rate was 4.5% per year compounded monthly.


the value of this investment after 7 years was equal to $24,650.14, as shown in the following online calculator display.


<img src = "http://theo.x10hosting.com/2018/092711.jpg" alt="$$$" >


when she turned 18, this amount was invested at 5% per year compounded monthly which she withdrew in monthly installments over the next 4 years.


the payment per month during the 4 year investment period was $567.68 as shown in the following online calculator display.


<img src = "http://theo.x10hosting.com/2018/092712.jpg" alt="$$$" >


the inputs to the first calculator display were:


present value = -18,000 (negative because it's money going out).
future value = 0
number of time periods = 7 * 12 = 84 months.
payment each time period = 0
payment at end of each time period (not used for future value analysis).


click on FV and the calculator tells you that the future value is $24,650.14.


the inputs to the second calculator display were:


present value = $24,650.14 (from the future value of the first calculator display).
future value = 0
number of time periods = 4 * 12 = 48 months.
payment each time period = 0
payment at end of each time period (used this time).


click on PMT and the calculator tells you that the monthly payment is $567.68.


the first use of the calculator found the value of the investment at the end of the 7 year investment period.


the second use of the calculator found the value of each monthly payment for the next 4 years.


i also used excel to provide a month by month analysis.


the critical time periods from the excel analysis are shown below:


<img src = "http://theo.x10hosting.com/2018/092713.jpg" alt="$$$" >


<img src = "http://theo.x10hosting.com/2018/092714.jpg" alt="$$$" >


<img src = "http://theo.x10hosting.com/2018/092715.jpg" alt="$$$" >


the analysis shows that her monthly installments were $567.68.


that should be your solution.