Simple Interest
Math MCQs

Question :    Calculate the amount due if Joseph borrowed a sum of $3700 at 9% simple interest for 4 years.

Correct Answer  $5032

Solution & Explanation

Solution

Given,

Principal (P) = $3700

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) = $3700 × 9% × 4

= $3700 ×⁹/₁₀₀ × 4

= ^{3700 × 9 × 4}/₁₀₀

= ^{33300 × 4}/₁₀₀

= ¹³³²⁰⁰/₁₀₀

= $1332

Thus, Simple Interest = $1332

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 = $3700 + $1332

= $5032

Thus, Amount to be paid = $5032 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 = $3700

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

And, Time (t) = 4 years

Thus, Amount (A)

= $3700 + ($3700 × 9% × 4)

= $3700 + ($3700 ×⁹/₁₀₀ × 4)

= $3700 + (^{3700 × 9 × 4}/₁₀₀)

= $3700 + (^{33300 × 4}/₁₀₀)

= $3700 + (¹³³²⁰⁰/₁₀₀)

= $3700 + $1332 = $5032

Thus, Amount (A) to be paid = $5032 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 $3700, the simple interest in 1 year

= ⁹/₁₀₀ × 3700

= ^{9 × 3700}/₁₀₀

= ³³³⁰⁰/₁₀₀ = $333

Thus, simple interest for 1 year = $333

Therefore, simple interest for 4 years

= Simple interest for 1 year × 4

= $333 × 4 = $1332

Thus, Simple Interest (SI) = $1332

Calculation of Amount

Amount = Principal + Interest

Thus, Amount = $3700 + $1332

= $5032

Thus, Amount to be paid = $5032 Answer

Similar Questions

(1) Mary took a loan of $4100 at the rate of 9% simple interest per annum. If he paid an amount of $6683 to clear the loan, then find the time period of the loan.

(2) Calculate the amount due if Jessica borrowed a sum of $3750 at 9% simple interest for 3 years.

(3) How much loan did Dorothy borrow 5 years ago at a rate of simple interest 3% per annum, if he paid $8337.5 to clear it?

(4) Calculate the amount due after 9 years if Barbara borrowed a sum of $5550 at a rate of 2% simple interest.

(5) How much loan did Christopher borrow 5 years ago at a rate of simple interest 5% per annum, if he paid $7500 to clear it?

(6) Calculate the amount due if Richard borrowed a sum of $3600 at 3% simple interest for 4 years.

(7) Nancy took a loan of $6300 at the rate of 10% simple interest per annum. If he paid an amount of $12600 to clear the loan, then find the time period of the loan.

(8) Sandra took a loan of $6900 at the rate of 8% simple interest per annum. If he paid an amount of $12420 to clear the loan, then find the time period of the loan.

(9) Sarah had to pay $4196.5 in order to furnish the loan taken 3 years before. If the rate of simple interest was 3% then find the sum borrowed.

(10) What amount does Robert have to pay after 6 years if he takes a loan of $3100 at 10% simple interest?