Simple Interest
Math MCQs

Question :    Calculate the amount due if Richard borrowed a sum of $3600 at 9% simple interest for 3 years.

Correct Answer  $4572

Solution & Explanation

Solution

Given,

Principal (P) = $3600

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) = $3600 × 9% × 3

= $3600 ×⁹/₁₀₀ × 3

= ^{3600 × 9 × 3}/₁₀₀

= ^{32400 × 3}/₁₀₀

= ⁹⁷²⁰⁰/₁₀₀

= $972

Thus, Simple Interest = $972

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 = $3600 + $972

= $4572

Thus, Amount to be paid = $4572 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 = $3600

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

And, Time (t) = 3 years

Thus, Amount (A)

= $3600 + ($3600 × 9% × 3)

= $3600 + ($3600 ×⁹/₁₀₀ × 3)

= $3600 + (^{3600 × 9 × 3}/₁₀₀)

= $3600 + (^{32400 × 3}/₁₀₀)

= $3600 + (⁹⁷²⁰⁰/₁₀₀)

= $3600 + $972 = $4572

Thus, Amount (A) to be paid = $4572 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 $3600, the simple interest in 1 year

= ⁹/₁₀₀ × 3600

= ^{9 × 3600}/₁₀₀

= ³²⁴⁰⁰/₁₀₀ = $324

Thus, simple interest for 1 year = $324

Therefore, simple interest for 3 years

= Simple interest for 1 year × 3

= $324 × 3 = $972

Thus, Simple Interest (SI) = $972

Calculation of Amount

Amount = Principal + Interest

Thus, Amount = $3600 + $972

= $4572

Thus, Amount to be paid = $4572 Answer

Similar Questions

(1) How much loan did Barbara borrow 5 years ago at a rate of simple interest 5% per annum, if he paid $6937.5 to clear it?

(2) Margaret took a loan of $6700 at the rate of 6% simple interest per annum. If he paid an amount of $9916 to clear the loan, then find the time period of the loan.

(3) Calculate the amount due after 9 years if Michael borrowed a sum of $5300 at a rate of 6% simple interest.

(4) If Elizabeth borrowed $3450 from a bank at a rate of 2% simple interest per annum then find the amount to be paid after 2 years.

(5) Linda took a loan of $4700 at the rate of 7% simple interest per annum. If he paid an amount of $7661 to clear the loan, then find the time period of the loan.

(6) Find the amount to be paid if Susan borrowed a sum of $5650 at 4% simple interest for 7 years.

(7) Nancy took a loan of $6300 at the rate of 8% simple interest per annum. If he paid an amount of $11340 to clear the loan, then find the time period of the loan.

(8) What amount does Christopher have to pay after 5 years if he takes a loan of $4000 at 10% simple interest?

(9) Calculate the amount due after 9 years if Richard borrowed a sum of $5600 at a rate of 2% simple interest.

(10) If Patricia paid $3528 to settle his loan which he had taken 4 years before at a simple interest of 3%, then find the loan taken.