Simple Interest
Math MCQs

Question :    Calculate the amount due if Michael borrowed a sum of $3300 at 9% simple interest for 3 years.

Correct Answer  $4191

Solution & Explanation

Solution

Given,

Principal (P) = $3300

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) = $3300 × 9% × 3

= $3300 ×⁹/₁₀₀ × 3

= ^{3300 × 9 × 3}/₁₀₀

= ^{29700 × 3}/₁₀₀

= ⁸⁹¹⁰⁰/₁₀₀

= $891

Thus, Simple Interest = $891

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 + $891

= $4191

Thus, Amount to be paid = $4191 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) = 3 years

Thus, Amount (A)

= $3300 + ($3300 × 9% × 3)

= $3300 + ($3300 ×⁹/₁₀₀ × 3)

= $3300 + (^{3300 × 9 × 3}/₁₀₀)

= $3300 + (^{29700 × 3}/₁₀₀)

= $3300 + (⁸⁹¹⁰⁰/₁₀₀)

= $3300 + $891 = $4191

Thus, Amount (A) to be paid = $4191 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 3 years

= Simple interest for 1 year × 3

= $297 × 3 = $891

Thus, Simple Interest (SI) = $891

Calculation of Amount

Amount = Principal + Interest

Thus, Amount = $3300 + $891

= $4191

Thus, Amount to be paid = $4191 Answer

Similar Questions

(1) Find the amount to be paid if David borrowed a sum of $5400 at 2% simple interest for 7 years.

(2) Calculate the amount due after 10 years if Thomas borrowed a sum of $5800 at a rate of 5% simple interest.

(3) Margaret took a loan of $6700 at the rate of 10% simple interest per annum. If he paid an amount of $12060 to clear the loan, then find the time period of the loan.

(4) Calculate the amount due after 10 years if James borrowed a sum of $5000 at a rate of 6% simple interest.

(5) Jessica took a loan of $5500 at the rate of 6% simple interest per annum. If he paid an amount of $8470 to clear the loan, then find the time period of the loan.

(6) Calculate the amount due if Richard borrowed a sum of $3600 at 2% simple interest for 3 years.

(7) Michael had to pay $3498 in order to furnish the loan taken 3 years before. If the rate of simple interest was 2% then find the sum borrowed.

(8) What amount will be due after 2 years if Matthew borrowed a sum of $3600 at a 5% simple interest?

(9) Calculate the amount due after 10 years if Karen borrowed a sum of $5950 at a rate of 2% simple interest.

(10) What amount does Karen have to pay after 6 years if he takes a loan of $3950 at 8% simple interest?