Simple Interest
Math MCQs

Question :    Calculate the amount due after 9 years if Robert borrowed a sum of $5100 at a rate of 2% simple interest.

Correct Answer  $6018

Solution & Explanation

Solution

Given,

Principal (P) = $5100

Rate of Simple Interest (SI) = 2%

Time (t) = 9 years

Thus, Amount (A) = ?

The Rate of Interest is always calculated per annum, i.e. per year.

Thus, here 2% simple interest means, Rate of Simple Interest (SI) is 2% per annum.

Method (1) Using Formula

Calculation of Simple Interest

Formula to Calculate Simple Interest

Simple Interest (SI) = Principal × Rate × Time

Thus, Simple Interest (SI) = $5100 × 2% × 9

= $5100 ײ/₁₀₀ × 9

= ^{5100 × 2 × 9}/₁₀₀

= ^{10200 × 9}/₁₀₀

= ⁹¹⁸⁰⁰/₁₀₀

= $918

Thus, Simple Interest = $918

Calculation of Amount

The total money paid to the lender by a borrower is called the Amount.

In other words, sum of priciple and interest is called the Amount.

Formula to Calculate the Amount

Amount = Principal + Interest

Thus, Amount = $5100 + $918

= $6018

Thus, Amount to be paid = $6018 Answer

Method (2)

Calculation of Amount when Principal, Rate of Simple Interest and Time are given

Calculation of Amount directly using Principal, SI, and Time

Formula to calculate the Amount

Amount (A) = Principal (P) + Principal(P) × Rate of Interest (SI) × Time (t)

⇒ A = P + PRT

Here in the question, P = $5100

Rate of Simple Interest (SI) or (R) = 2%

And, Time (t) = 9 years

Thus, Amount (A)

= $5100 + ($5100 × 2% × 9)

= $5100 + ($5100 ײ/₁₀₀ × 9)

= $5100 + (^{5100 × 2 × 9}/₁₀₀)

= $5100 + (^{10200 × 9}/₁₀₀)

= $5100 + (⁹¹⁸⁰⁰/₁₀₀)

= $5100 + $918 = $6018

Thus, Amount (A) to be paid = $6018 Answer

Method (3) Unitary Method

Calculation of Amount using Unitary Method

Calculation of Interest using Unitary Method

Here, given Rate of Simple Interest = 2%

This, means, $2 per $100 per year

∵ For $100, the simple interest for 1 year = $2

∴ For $1, the simple interest for 1 year = ²/₁₀₀

∴ For $5100, the simple interest in 1 year

= ²/₁₀₀ × 5100

= ^{2 × 5100}/₁₀₀

= ¹⁰²⁰⁰/₁₀₀ = $102

Thus, simple interest for 1 year = $102

Therefore, simple interest for 9 years

= Simple interest for 1 year × 9

= $102 × 9 = $918

Thus, Simple Interest (SI) = $918

Calculation of Amount

Amount = Principal + Interest

Thus, Amount = $5100 + $918

= $6018

Thus, Amount to be paid = $6018 Answer

Similar Questions

(1) In how much time a principal of $3200 will amount to $3392 at a simple interest of 2% per annum?

(2) Susan took a loan of $5300 at the rate of 6% simple interest per annum. If he paid an amount of $7526 to clear the loan, then find the time period of the loan.

(3) Calculate the amount due if Elizabeth borrowed a sum of $3450 at 8% simple interest for 3 years.

(4) Margaret took a loan of $6700 at the rate of 6% simple interest per annum. If he paid an amount of $10720 to clear the loan, then find the time period of the loan.

(5) Robert took a loan of $4200 at the rate of 9% simple interest per annum. If he paid an amount of $7224 to clear the loan, then find the time period of the loan.

(6) Margaret had to pay $4741.5 in order to furnish the loan taken 3 years before. If the rate of simple interest was 3% then find the sum borrowed.

(7) Michael took a loan of $4600 at the rate of 6% simple interest per annum. If he paid an amount of $7084 to clear the loan, then find the time period of the loan.

(8) Thomas took a loan of $5600 at the rate of 6% simple interest per annum. If he paid an amount of $8960 to clear the loan, then find the time period of the loan.

(9) Mark took a loan of $6800 at the rate of 6% simple interest per annum. If he paid an amount of $9656 to clear the loan, then find the time period of the loan.

(10) Calculate the amount due after 9 years if Jennifer borrowed a sum of $5250 at a rate of 8% simple interest.