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

(2) Calculate the amount due after 9 years if Linda borrowed a sum of $5350 at a rate of 6% simple interest.

(3) How much loan did Margaret borrow 5 years ago at a rate of simple interest 2% per annum, if he paid $6985 to clear it?

(4) Find the amount to be paid if Richard borrowed a sum of $5600 at 5% simple interest for 7 years.

(5) Calculate the amount due if Patricia borrowed a sum of $3150 at 6% simple interest for 3 years.

(6) How much loan did Ronald borrow 5 years ago at a rate of simple interest 5% per annum, if he paid $9375 to clear it?

(7) Find the amount to be paid if Patricia borrowed a sum of $5150 at 3% simple interest for 8 years.

(8) Patricia took a loan of $4300 at the rate of 10% simple interest per annum. If he paid an amount of $7310 to clear the loan, then find the time period of the loan.

(9) Richard took a loan of $5200 at the rate of 9% simple interest per annum. If he paid an amount of $8944 to clear the loan, then find the time period of the loan.

(10) Betty took a loan of $6500 at the rate of 10% simple interest per annum. If he paid an amount of $11700 to clear the loan, then find the time period of the loan.