Math

QuestionCalculate and compare interest for Laura's compound and Eric's simple interest on \$70,000 at 3\% for 3 years.

Studdy Solution

STEP 1

Assumptions1. Laura's account compounds interest annually. . Eric's account earns simple interest.
3. Both Laura and Eric deposit $70,000.
4. The annual interest rate for both accounts is3%.
5. There are no withdrawals and no additional deposits.
6. We need to calculate the interest earned for each of the first three years.

STEP 2

First, we need to understand the formulas for calculating simple and compound interest.
For simple interestInterest=Principal×Rate×TimeInterest = Principal \times Rate \times TimeFor compound interestAmount=Principal×(1+Rate)TimeAmount = Principal \times (1 + Rate)^{Time}Then, to find the interest, subtract the principal from the amount.

STEP 3

Let's calculate the simple interest for Eric for each of the first three years.
For year1Interest=$70,000×3%×1Interest = \$70,000 \times3\% \times1For year2Interest=$70,000×3%×1Interest = \$70,000 \times3\% \times1For year3Interest=$70,000×3%×1Interest = \$70,000 \times3\% \times1

STEP 4

Convert the percentage to a decimal value.
3%=0.033\% =0.03Then, calculate the interest for each year.

STEP 5

Calculate the simple interest for Eric for each of the first three years.
For year1Interest=$70,000×0.03×1=$2,100Interest = \$70,000 \times0.03 \times1 = \$2,100For year2Interest=$70,000×0.03×1=$2,100Interest = \$70,000 \times0.03 \times1 = \$2,100For year3Interest=$70,000×0.03×1=$2,100Interest = \$70,000 \times0.03 \times1 = \$2,100

STEP 6

Now, let's calculate the compound interest for Laura for each of the first three years.
For year1Amount=$70,000×(1+0.03)1Amount = \$70,000 \times (1 +0.03)^1Interest=AmountPrincipalInterest = Amount - PrincipalFor year2Amount=$70,000×(1+0.03)2Amount = \$70,000 \times (1 +0.03)^2Interest=AmountPrincipalInterest = Amount - PrincipalFor year3Amount=$70,000×(1+0.03)3Amount = \$70,000 \times (1 +0.03)^3Interest=AmountPrincipalInterest = Amount - Principal

STEP 7

Calculate the compound interest for Laura for each of the first three years.
For year1Amount=$70,000×(1+0.03)1=$72,100Amount = \$70,000 \times (1 +0.03)^1 = \$72,100Interest=$72,100$70,000=$2,100Interest = \$72,100 - \$70,000 = \$2,100For year2Amount=$70,000×(1+0.03)2=$74,263Amount = \$70,000 \times (1 +0.03)^2 = \$74,263Interest=$74,263$70,000=$4,263Interest = \$74,263 - \$70,000 = \$4,263For year3Amount=$70,000×(1+0.03)3=$76,490.89Amount = \$70,000 \times (1 +0.03)^3 = \$76,490.89Interest=$76,490.89$70,000=$6,490.89Interest = \$76,490.89 - \$70,000 = \$6,490.89

STEP 8

Now, let's compare the interest earned by Laura and Eric for each of the first three years.
For year1, both Laura and Eric earn \$2,100.
For year2, Laura earns \$4,263 and Eric earns \$2,100. Laura earns more.
For year3, Laura earns \$6,490.89 and Eric earns \$2,100. Laura earns more.
So, Laura earns more interest than Eric for each year after the first year.

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