Simple Interest
Math MCQs

Question :    Calculate the amount due if Michael borrowed a sum of $3300 at 9% simple interest for 4 years.

Correct Answer  $4488

Solution & Explanation

Solution

Given,

Principal (P) = $3300

Rate of Simple Interest (SI) = 9%

Time (t) = 4 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) = $3300 × 9% × 4

= $3300 ×⁹/₁₀₀ × 4

= ^{3300 × 9 × 4}/₁₀₀

= ^{29700 × 4}/₁₀₀

= ¹¹⁸⁸⁰⁰/₁₀₀

= $1188

Thus, Simple Interest = $1188

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 = $3300 + $1188

= $4488

Thus, Amount to be paid = $4488 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 = $3300

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

And, Time (t) = 4 years

Thus, Amount (A)

= $3300 + ($3300 × 9% × 4)

= $3300 + ($3300 ×⁹/₁₀₀ × 4)

= $3300 + (^{3300 × 9 × 4}/₁₀₀)

= $3300 + (^{29700 × 4}/₁₀₀)

= $3300 + (¹¹⁸⁸⁰⁰/₁₀₀)

= $3300 + $1188 = $4488

Thus, Amount (A) to be paid = $4488 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 $3300, the simple interest in 1 year

= ⁹/₁₀₀ × 3300

= ^{9 × 3300}/₁₀₀

= ²⁹⁷⁰⁰/₁₀₀ = $297

Thus, simple interest for 1 year = $297

Therefore, simple interest for 4 years

= Simple interest for 1 year × 4

= $297 × 4 = $1188

Thus, Simple Interest (SI) = $1188

Calculation of Amount

Amount = Principal + Interest

Thus, Amount = $3300 + $1188

= $4488

Thus, Amount to be paid = $4488 Answer

Similar Questions

(1) If Ashley paid $5460 to settle his loan which he had taken 4 years before at a simple interest of 5%, then find the loan taken.

(2) Elizabeth took a loan of $4900 at the rate of 6% simple interest per annum. If he paid an amount of $7546 to clear the loan, then find the time period of the loan.

(3) If Susan paid $4234 to settle his loan which he had taken 4 years before at a simple interest of 4%, then find the loan taken.

(4) Calculate the amount due after 9 years if Charles borrowed a sum of $5900 at a rate of 6% simple interest.

(5) Calculate the amount due after 10 years if Elizabeth borrowed a sum of $5450 at a rate of 5% simple interest.

(6) Karen took a loan of $5900 at the rate of 9% simple interest per annum. If he paid an amount of $10679 to clear the loan, then find the time period of the loan.

(7) Find the amount to be paid if Robert borrowed a sum of $5100 at 3% simple interest for 8 years.

(8) What amount does Robert have to pay after 5 years if he takes a loan of $3100 at 2% simple interest?

(9) Michelle had to pay $5544 in order to furnish the loan taken 3 years before. If the rate of simple interest was 4% then find the sum borrowed.

(10) Find the amount to be paid if Karen borrowed a sum of $5950 at 8% simple interest for 7 years.