Math Problem Statement

You deposit $300 each month into an account earning 4% interest compounded monthly. a) How much will you have in the account in 20 years? b) How much total money will you put into the account? c) How much total interest will you earn?

Solution

To solve the problem, let's break it into steps:

Key Information:

  • Monthly Deposit (PP) = $300
  • Annual Interest Rate (rr) = 4% = 0.04
  • Compounding Periods per Year = 12 (monthly)
  • Time Period (tt) = 20 years

Formula for Future Value of a Series (Compound Interest):

The formula for the future value of monthly deposits is: FV=P(1+rn)nt1rnFV = P \cdot \frac{(1 + \frac{r}{n})^{n \cdot t} - 1}{\frac{r}{n}} Where:

  • PP = monthly deposit
  • rr = annual interest rate
  • nn = compounding periods per year
  • tt = total time in years

Now, let's calculate each part:


(a) How much will you have in the account in 20 years?

FV=300(1+0.0412)122010.0412FV = 300 \cdot \frac{(1 + \frac{0.04}{12})^{12 \cdot 20} - 1}{\frac{0.04}{12}}


(b) Total money deposited into the account:

The total money deposited is simply: Total Deposits=Pnt\text{Total Deposits} = P \cdot n \cdot t


(c) Total interest earned:

Interest=Future ValueTotal Deposits\text{Interest} = \text{Future Value} - \text{Total Deposits}

Let me calculate these values for you.# Given values P = 300 # monthly deposit in dollars r = 0.04 # annual interest rate (4%) n = 12 # number of compounding periods per year (monthly) t = 20 # time in years

Future Value calculation

FV = P * (((1 + r / n)**(n * t) - 1) / (r / n))

Total money deposited

total_deposits = P * n * t

Total interest earned

total_interest = FV - total_deposits

FV, total_deposits, total_interest(110032.38782697874, 72000, 38032.38782697874)(110032.38782697874, 72000, 38032.38782697874)success### Results: (a) Amount in the account in 20 years: $110,032.39
(b) Total money deposited into the account: $72,000
(c) Total interest earned: $38,032.39

Would you like more details on the calculations or assistance with related questions?

Here are 5 related questions you might explore:

  1. How does changing the monthly deposit affect the final amount?
  2. What if the interest was compounded quarterly instead of monthly?
  3. How would a higher annual interest rate (e.g., 6%) impact the final amount?
  4. How much time would it take to reach $150,000 with the same monthly deposit?
  5. How does compounding frequency affect interest growth over time?

Tip: Consistent savings, even with small amounts, can grow significantly over time due to compound interest!

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Math Problem Analysis

Mathematical Concepts

Compound Interest
Future Value of a Series
Arithmetic Operations

Formulas

Future Value (FV) = P * [(1 + r/n)^(n*t) - 1] / (r/n)
Total Deposits = P * n * t
Interest Earned = Future Value - Total Deposits

Theorems

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Suitable Grade Level

Grades 10-12