Simple Interest
Math MCQs

Question :    Calculate the amount due after 9 years if Barbara borrowed a sum of $5550 at a rate of 8% simple interest.

Correct Answer  $9546

Solution & Explanation

Solution

Given,

Principal (P) = $5550

Rate of Simple Interest (SI) = 8%

Time (t) = 9 years

Thus, Amount (A) = ?

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

Thus, here 8% simple interest means, Rate of Simple Interest (SI) is 8% 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) = $5550 × 8% × 9

= $5550 ×⁸/₁₀₀ × 9

= ^{5550 × 8 × 9}/₁₀₀

= ^{44400 × 9}/₁₀₀

= ³⁹⁹⁶⁰⁰/₁₀₀

= $3996

Thus, Simple Interest = $3996

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 = $5550 + $3996

= $9546

Thus, Amount to be paid = $9546 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 = $5550

Rate of Simple Interest (SI) or (R) = 8%

And, Time (t) = 9 years

Thus, Amount (A)

= $5550 + ($5550 × 8% × 9)

= $5550 + ($5550 ×⁸/₁₀₀ × 9)

= $5550 + (^{5550 × 8 × 9}/₁₀₀)

= $5550 + (^{44400 × 9}/₁₀₀)

= $5550 + (³⁹⁹⁶⁰⁰/₁₀₀)

= $5550 + $3996 = $9546

Thus, Amount (A) to be paid = $9546 Answer

Method (3) Unitary Method

Calculation of Amount using Unitary Method

Calculation of Interest using Unitary Method

Here, given Rate of Simple Interest = 8%

This, means, $8 per $100 per year

∵ For $100, the simple interest for 1 year = $8

∴ For $1, the simple interest for 1 year = ⁸/₁₀₀

∴ For $5550, the simple interest in 1 year

= ⁸/₁₀₀ × 5550

= ^{8 × 5550}/₁₀₀

= ⁴⁴⁴⁰⁰/₁₀₀ = $444

Thus, simple interest for 1 year = $444

Therefore, simple interest for 9 years

= Simple interest for 1 year × 9

= $444 × 9 = $3996

Thus, Simple Interest (SI) = $3996

Calculation of Amount

Amount = Principal + Interest

Thus, Amount = $5550 + $3996

= $9546

Thus, Amount to be paid = $9546 Answer

Similar Questions

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

(2) How much loan did Jennifer borrow 5 years ago at a rate of simple interest 5% per annum, if he paid $6562.5 to clear it?

(3) Calculate the amount due after 9 years if John borrowed a sum of $5200 at a rate of 5% simple interest.

(4) In how much time a principal of $3050 will amount to $3294 at a simple interest of 2% per annum?

(5) If Nancy paid $4980 to settle his loan which he had taken 4 years before at a simple interest of 5%, then find the loan taken.

(6) What amount does Barbara have to pay after 5 years if he takes a loan of $3550 at 6% simple interest?

(7) Find the amount to be paid if Karen borrowed a sum of $5950 at 5% simple interest for 7 years.

(8) Thomas took a loan of $5600 at the rate of 9% simple interest per annum. If he paid an amount of $9128 to clear the loan, then find the time period of the loan.

(9) Find the amount to be paid if Charles borrowed a sum of $5900 at 5% simple interest for 8 years.

(10) Calculate the amount due if Michael borrowed a sum of $3300 at 7% simple interest for 3 years.