Simple Interest
Math MCQs

Question :    Calculate the amount due if Charles borrowed a sum of $3900 at 6% simple interest for 3 years.

Correct Answer  $4602

Solution & Explanation

Solution

Given,

Principal (P) = $3900

Rate of Simple Interest (SI) = 6%

Time (t) = 3 years

Thus, Amount (A) = ?

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

Thus, here 6% simple interest means, Rate of Simple Interest (SI) is 6% 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) = $3900 × 6% × 3

= $3900 ×⁶/₁₀₀ × 3

= ^{3900 × 6 × 3}/₁₀₀

= ^{23400 × 3}/₁₀₀

= ⁷⁰²⁰⁰/₁₀₀

= $702

Thus, Simple Interest = $702

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 = $3900 + $702

= $4602

Thus, Amount to be paid = $4602 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 = $3900

Rate of Simple Interest (SI) or (R) = 6%

And, Time (t) = 3 years

Thus, Amount (A)

= $3900 + ($3900 × 6% × 3)

= $3900 + ($3900 ×⁶/₁₀₀ × 3)

= $3900 + (^{3900 × 6 × 3}/₁₀₀)

= $3900 + (^{23400 × 3}/₁₀₀)

= $3900 + (⁷⁰²⁰⁰/₁₀₀)

= $3900 + $702 = $4602

Thus, Amount (A) to be paid = $4602 Answer

Method (3) Unitary Method

Calculation of Amount using Unitary Method

Calculation of Interest using Unitary Method

Here, given Rate of Simple Interest = 6%

This, means, $6 per $100 per year

∵ For $100, the simple interest for 1 year = $6

∴ For $1, the simple interest for 1 year = ⁶/₁₀₀

∴ For $3900, the simple interest in 1 year

= ⁶/₁₀₀ × 3900

= ^{6 × 3900}/₁₀₀

= ²³⁴⁰⁰/₁₀₀ = $234

Thus, simple interest for 1 year = $234

Therefore, simple interest for 3 years

= Simple interest for 1 year × 3

= $234 × 3 = $702

Thus, Simple Interest (SI) = $702

Calculation of Amount

Amount = Principal + Interest

Thus, Amount = $3900 + $702

= $4602

Thus, Amount to be paid = $4602 Answer

Similar Questions

(1) What amount will be due after 2 years if Andrew borrowed a sum of $3900 at a 4% simple interest?

(2) Calculate the amount due if Michael borrowed a sum of $3300 at 10% simple interest for 4 years.

(3) Calculate the amount due if Barbara borrowed a sum of $3550 at 2% simple interest for 3 years.

(4) Barbara took a loan of $5100 at the rate of 7% simple interest per annum. If he paid an amount of $7599 to clear the loan, then find the time period of the loan.

(5) Calculate the amount due if Jennifer borrowed a sum of $3250 at 2% simple interest for 3 years.

(6) In how much time a principal of $3000 will amount to $3120 at a simple interest of 2% per annum?

(7) Calculate the amount due if James borrowed a sum of $3000 at 7% simple interest for 4 years.

(8) If Richard paid $4032 to settle his loan which he had taken 4 years before at a simple interest of 3%, then find the loan taken.

(9) Sandra had to pay $4717 in order to furnish the loan taken 3 years before. If the rate of simple interest was 2% then find the sum borrowed.

(10) If Steven paid $4968 to settle his loan which he had taken 4 years before at a simple interest of 2%, then find the loan taken.