Simple Interest
Math MCQs

Question :    Find the amount to be paid if Charles borrowed a sum of $5900 at 3% simple interest for 7 years.

Correct Answer  $7139

Solution & Explanation

Solution

Given,

Principal (P) = $5900

Rate of Simple Interest (SI) = 3%

Time (t) = 7 years

Thus, Amount (A) = ?

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

Thus, here 3% simple interest means, Rate of Simple Interest (SI) is 3% 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) = $5900 × 3% × 7

= $5900 ׳/₁₀₀ × 7

= ^{5900 × 3 × 7}/₁₀₀

= ^{17700 × 7}/₁₀₀

= ¹²³⁹⁰⁰/₁₀₀

= $1239

Thus, Simple Interest = $1239

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 = $5900 + $1239

= $7139

Thus, Amount to be paid = $7139 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 = $5900

Rate of Simple Interest (SI) or (R) = 3%

And, Time (t) = 7 years

Thus, Amount (A)

= $5900 + ($5900 × 3% × 7)

= $5900 + ($5900 ׳/₁₀₀ × 7)

= $5900 + (^{5900 × 3 × 7}/₁₀₀)

= $5900 + (^{17700 × 7}/₁₀₀)

= $5900 + (¹²³⁹⁰⁰/₁₀₀)

= $5900 + $1239 = $7139

Thus, Amount (A) to be paid = $7139 Answer

Method (3) Unitary Method

Calculation of Amount using Unitary Method

Calculation of Interest using Unitary Method

Here, given Rate of Simple Interest = 3%

This, means, $3 per $100 per year

∵ For $100, the simple interest for 1 year = $3

∴ For $1, the simple interest for 1 year = ³/₁₀₀

∴ For $5900, the simple interest in 1 year

= ³/₁₀₀ × 5900

= ^{3 × 5900}/₁₀₀

= ¹⁷⁷⁰⁰/₁₀₀ = $177

Thus, simple interest for 1 year = $177

Therefore, simple interest for 7 years

= Simple interest for 1 year × 7

= $177 × 7 = $1239

Thus, Simple Interest (SI) = $1239

Calculation of Amount

Amount = Principal + Interest

Thus, Amount = $5900 + $1239

= $7139

Thus, Amount to be paid = $7139 Answer

Similar Questions

(1) Find the amount to be paid if Joseph borrowed a sum of $5700 at 8% simple interest for 7 years.

(2) In how much time a principal of $3050 will amount to $3660 at a simple interest of 4% per annum?

(3) Find the amount to be paid if John borrowed a sum of $5200 at 9% simple interest for 8 years.

(4) Calculate the amount due after 10 years if Richard borrowed a sum of $5600 at a rate of 7% simple interest.

(5) Calculate the amount due if James borrowed a sum of $3000 at 2% simple interest for 3 years.

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

(7) How much loan did Deborah borrow 5 years ago at a rate of simple interest 2% per annum, if he paid $8195 to clear it?

(8) Calculate the amount due if David borrowed a sum of $3400 at 7% simple interest for 3 years.

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

(10) What amount does David have to pay after 5 years if he takes a loan of $3400 at 4% simple interest?