Round any decimals to the nearest penny. You save $8500. You place 40% in a savings account earning 4.2% APR compounded

annually and the rest in a stock plan. The stock plan decreases 3% in the first year and increases 7.5% in the second year.
What is the total gain at the end of the second year for both accounts combined?

1 answer

To calculate the total gain at the end of the second year for both accounts, we can follow these steps:

  1. Calculate how much money is placed in the savings account and how much is placed in the stock plan.
  2. Calculate the final amount in the savings account after two years.
  3. Calculate the final amount in the stock plan after two years.
  4. Determine the total gain from both accounts.

Step 1: Calculate amounts in both accounts

  • Total savings: \(8500\)

  • Amount in savings account: \(40%\) of \(8500\)

    \[ \text{Savings amount} = 8500 \times 0.40 = 3400 \]

  • Amount in stock plan: \(60%\) of \(8500\)

    \[ \text{Stock plan amount} = 8500 \times 0.60 = 5100 \]

Step 2: Calculate final amount in savings account

The formula for the amount in a savings account with compounded interest is:

\[ A = P(1 + r)^t \]

Where:

  • \(A\) is the amount of money accumulated after \(n\) years, including interest.
  • \(P\) is the principal amount (the initial amount of money).
  • \(r\) is the annual interest rate (decimal).
  • \(t\) is the number of years the money is invested or borrowed.
  1. For the savings account after 2 years:
    • \(P = 3400\)
    • \(r = 0.042\)
    • \(t = 2\)

Calculating:

\[ A_{savings} = 3400(1 + 0.042)^2 \] \[ A_{savings} = 3400(1.042)^2 \] \[ A_{savings} = 3400 \times 1.086736 = 3694.50 \quad (\text{rounding to the nearest penny}) \]

Step 3: Calculate final amount in stock plan

  1. First year (decrease of 3%):
    • Final amount after first year:

\[ A_{stock1} = 5100 \times (1 - 0.03) = 5100 \times 0.97 = 4957.00 \]

  1. Second year (increase of 7.5%):
    • Final amount after second year:

\[ A_{stock2} = 4957.00 \times (1 + 0.075) = 4957.00 \times 1.075 = 5325.48 \quad (\text{rounding to the nearest penny}) \]

Step 4: Calculate total gain at the end of the second year

  1. Total amount from both accounts:

\[ \text{Total amount} = A_{savings} + A_{stock2} = 3694.50 + 5325.48 = 9019.98 \]

  1. Total gain:

\[ \text{Total gain} = \text{Total amount} - \text{Initial savings} = 9019.98 - 8500 = 519.98 \]

Final Result

The total gain at the end of the second year for both accounts combined is $519.98.