Juliana plans to invest money for 10 years in an account paying 3.5% interest, compounded annually. She expects the annual inflation rate to be 2% per year throughout the 10-year period. Juliana would like her investment to be worth a real value of $ € 4000$, compared to current values, at the end of the 10-year period. She is considering two options.

Question
SLPaper 1

Juliana plans to invest money for 10 years in an account paying 3.5% interest, compounded annually. She expects the annual inflation rate to be 2% per year throughout the 10-year period. Juliana would like her investment to be worth a real value of 4000 € 4000, compared to current values, at the end of the 10-year period. She is considering two options.

  • Option 1: Make a one-time investment at the start of the 10-year period.
  • Option 2: Invest 1000€1000 at the start of the 10-year period and then invest $x into the account at the end of each year (including the first and last years).
1.

For option 1, determine the minimum amount Juliana would need to invest. Give your answer to the nearest dollar.

[3]
Verified
Solution

METHOD 1 - (with FV=4000FV=4000)

EITHER

N=10N=10 I=1.5\\I=1.5 FV=4000\\FV=4000 P/Y=1\\P/Y=1 C/Y=1\\C/Y=1 A1 M1

Note: Award A1 for (3.52=)1.5(3.5-2=) 1.5 seen and M1 for all other entries correct.

OR

4000=A(1+0.015)104000=A(1+0.015)^{10} A1 M1

Note: Award A1 for 1.5 or 0.015 seen, M1 for attempt to substitute into compound interest formula and equating to 4000.

THEN

PV=3447PV=3447 A1

Note: Award A0 if not rounded to a whole number or a negative sign given.

METHOD 2 - (With FV including inflation)

calculate FV with inflation 4000×1.02104000 \times 1.02^{10} A1

(=4875.977...)(=4875.977...)

EITHER

4000×1.0210=PV×1.035104000 \times 1.02^{10}=PV \times 1.035^{10} M1

OR

N=10N=10 I=3.5\\I=3.5 FV=4875.977..\\FV=4875.977.. P/Y=1\\P/Y=1 C/Y=1\\C/Y=1 M1

Note: Award M1 for their FV and all other entries correct.

THEN

PV=3457PV=3457 A1

Note: Award A0 if not rounded to a whole number or a negative sign given.

METHOD 3 - (Using formula to calculate real rate of return)

real rate of return == 1.47058...(%)1.47058...(\%) A1

EITHER

4000=PV×1.0147058...104000=PV \times 1.0147058...^{10} M1

OR

N=10N=10 I=1.47058...\\I=1.47058... FV=4000\\FV=4000 P/Y=1\\P/Y=1 C/Y=1\\C/Y=1 M1

Note: Award M1 for all entries correct.

THEN

PV=3457PV = 3457 A1

2.

For option 2, find the minimum value of x that Juliana would need to invest each year. Give your answer to the nearest dollar.

[3]
Verified
Solution

METHOD 1 - (Finding the future value of the investment using PV from part (a))

N=10N=10 I=3.5\\I=3.5 PV=3446.66...\\PV=3446.66... from Method (1) OR 3456.67...3456.67...(from Methods 2, 3) P/Y=1\\P/Y=1 C/Y=1\\C/Y=1 M1

Note: Award M1 for interest rate 3.5 and answer to part (a) as PV.

FV=4861.87FV=4861.87 OR 4875.974875.97 A1

so payment required (from TVM) will be \294OROR$295$ A1

Note: Award A0 if a negative sign given, unless already penalized in part (a).

METHOD 2 - (Using FV)

N=10N=10 I=3.5\\I=3.5 PV=1000\\PV=-1000 FV=4875.977...\\FV=4875.977... P/Y=1\\P/Y=1 C/Y=1\\C/Y=1 A1 M1

Note: Award A1 for I=3.5I=3.5 and FV=±4875.977...FV= \pm 4875.977..., M1 for all other entries correct and opposite PV and FV signs.

PMT=295(295.393)PMT = 295(295.393) A1

Note: Correct 3sf answer is 295, however accept an answer of 296 given that the context supports rounding up. Award A0 if a negative sign given, unless already penalized in part (a).

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