Math Problem Statement

Find the accumulated present value of an investment over a 9 year period if there is a continuous money flow of $7,000 per year and the interest rate is 0.7% compounded continuously.

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Solution

To find the accumulated present value of an investment under a continuous money flow, we use the formula:

PV=0TRertdtPV = \int_0^T R e^{-rt} \, dt

Where:

  • R=7,000R = 7,000 (continuous annual money flow),
  • r=0.007r = 0.007 (interest rate compounded continuously),
  • T=9T = 9 (time period in years).

Substitute the values into the formula:

PV=097000e0.007tdtPV = \int_0^9 7000 e^{-0.007t} \, dt

Step 1: Evaluate the integral

The integral of erte^{-rt} is: ertdt=ertr\int e^{-rt} \, dt = \frac{e^{-rt}}{-r}

Thus: PV=7000[e0.007t0.007]09PV = 7000 \left[ \frac{e^{-0.007t}}{-0.007} \right]_0^9

Step 2: Simplify the expression

Factor 10.007-\frac{1}{0.007} outside: PV=70000.007[e0.007t]09PV = -\frac{7000}{0.007} \left[ e^{-0.007t} \right]_0^9

PV=1000000[e0.007t]09PV = -1000000 \left[ e^{-0.007t} \right]_0^9

Step 3: Evaluate the bounds

PV=1000000(e0.0079e0.0070)PV = -1000000 \left( e^{-0.007 \cdot 9} - e^{-0.007 \cdot 0} \right)

PV=1000000(e0.0631)PV = -1000000 \left( e^{-0.063} - 1 \right)

Using e0.0630.9389e^{-0.063} \approx 0.9389: PV=1000000(0.93891)PV = -1000000 \left( 0.9389 - 1 \right)

PV=1000000(0.0611)PV = -1000000 \cdot (-0.0611)

PV=61100PV = 61100

Final Answer:

The accumulated present value of the investment is $61,100.


Would you like me to explain further or explore alternative scenarios?
Here are 5 related questions for further exploration:

  1. How does the result change if the interest rate increases to 1%?
  2. What would the accumulated value be if the continuous flow was $10,000 annually?
  3. How do you compute future value under similar continuous flow conditions?
  4. How would the calculation change if the flow ceased after 5 years instead of 9 years?
  5. Can this formula apply to investments with a varying flow rate? If so, how?

Tip: Always ensure the interest rate aligns with the compounding method when solving time value of money problems.

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Math Problem Analysis

Mathematical Concepts

Continuous Compounding
Present Value
Integral Calculus

Formulas

PV = ∫₀ᵀ R e^(-rt) dt
∫ e^(-rt) dt = (e^(-rt)) / (-r)

Theorems

Exponential Decay
Fundamental Theorem of Calculus

Suitable Grade Level

Grades 11-12 and College