Simple Interest
Math MCQs

Question :    Calculate the amount due if Joseph borrowed a sum of $3700 at 9% simple interest for 3 years.

Correct Answer  $4699

Solution & Explanation

Solution

Given,

Principal (P) = $3700

Rate of Simple Interest (SI) = 9%

Time (t) = 3 years

Thus, Amount (A) = ?

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

Thus, here 9% simple interest means, Rate of Simple Interest (SI) is 9% 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) = $3700 × 9% × 3

= $3700 ×⁹/₁₀₀ × 3

= ^{3700 × 9 × 3}/₁₀₀

= ^{33300 × 3}/₁₀₀

= ⁹⁹⁹⁰⁰/₁₀₀

= $999

Thus, Simple Interest = $999

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 = $3700 + $999

= $4699

Thus, Amount to be paid = $4699 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 = $3700

Rate of Simple Interest (SI) or (R) = 9%

And, Time (t) = 3 years

Thus, Amount (A)

= $3700 + ($3700 × 9% × 3)

= $3700 + ($3700 ×⁹/₁₀₀ × 3)

= $3700 + (^{3700 × 9 × 3}/₁₀₀)

= $3700 + (^{33300 × 3}/₁₀₀)

= $3700 + (⁹⁹⁹⁰⁰/₁₀₀)

= $3700 + $999 = $4699

Thus, Amount (A) to be paid = $4699 Answer

Method (3) Unitary Method

Calculation of Amount using Unitary Method

Calculation of Interest using Unitary Method

Here, given Rate of Simple Interest = 9%

This, means, $9 per $100 per year

∵ For $100, the simple interest for 1 year = $9

∴ For $1, the simple interest for 1 year = ⁹/₁₀₀

∴ For $3700, the simple interest in 1 year

= ⁹/₁₀₀ × 3700

= ^{9 × 3700}/₁₀₀

= ³³³⁰⁰/₁₀₀ = $333

Thus, simple interest for 1 year = $333

Therefore, simple interest for 3 years

= Simple interest for 1 year × 3

= $333 × 3 = $999

Thus, Simple Interest (SI) = $999

Calculation of Amount

Amount = Principal + Interest

Thus, Amount = $3700 + $999

= $4699

Thus, Amount to be paid = $4699 Answer

Similar Questions

(1) Jessica had to pay $4312.5 in order to furnish the loan taken 3 years before. If the rate of simple interest was 5% then find the sum borrowed.

(2) James took a loan of $4000 at the rate of 10% simple interest per annum. If he paid an amount of $6800 to clear the loan, then find the time period of the loan.

(3) Calculate the amount due after 10 years if Jessica borrowed a sum of $5750 at a rate of 2% simple interest.

(4) How much loan did Donald borrow 5 years ago at a rate of simple interest 4% per annum, if he paid $7800 to clear it?

(5) What amount does Jennifer have to pay after 6 years if he takes a loan of $3250 at 10% simple interest?

(6) What amount does Michael have to pay after 5 years if he takes a loan of $3300 at 3% simple interest?

(7) Find the amount to be paid if Thomas borrowed a sum of $5800 at 3% simple interest for 8 years.

(8) Calculate the amount due if James borrowed a sum of $3000 at 2% simple interest for 3 years.

(9) What amount does Patricia have to pay after 5 years if he takes a loan of $3150 at 7% simple interest?

(10) Calculate the amount due if William borrowed a sum of $3500 at 9% simple interest for 3 years.