Simple Interest
Math MCQs

Question :    Calculate the amount due if Elizabeth borrowed a sum of $3450 at 6% simple interest for 4 years.

Correct Answer  $4278

Solution & Explanation

Solution

Given,

Principal (P) = $3450

Rate of Simple Interest (SI) = 6%

Time (t) = 4 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) = $3450 × 6% × 4

= $3450 ×⁶/₁₀₀ × 4

= ^{3450 × 6 × 4}/₁₀₀

= ^{20700 × 4}/₁₀₀

= ⁸²⁸⁰⁰/₁₀₀

= $828

Thus, Simple Interest = $828

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 = $3450 + $828

= $4278

Thus, Amount to be paid = $4278 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 = $3450

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

And, Time (t) = 4 years

Thus, Amount (A)

= $3450 + ($3450 × 6% × 4)

= $3450 + ($3450 ×⁶/₁₀₀ × 4)

= $3450 + (^{3450 × 6 × 4}/₁₀₀)

= $3450 + (^{20700 × 4}/₁₀₀)

= $3450 + (⁸²⁸⁰⁰/₁₀₀)

= $3450 + $828 = $4278

Thus, Amount (A) to be paid = $4278 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 $3450, the simple interest in 1 year

= ⁶/₁₀₀ × 3450

= ^{6 × 3450}/₁₀₀

= ²⁰⁷⁰⁰/₁₀₀ = $207

Thus, simple interest for 1 year = $207

Therefore, simple interest for 4 years

= Simple interest for 1 year × 4

= $207 × 4 = $828

Thus, Simple Interest (SI) = $828

Calculation of Amount

Amount = Principal + Interest

Thus, Amount = $3450 + $828

= $4278

Thus, Amount to be paid = $4278 Answer

Similar Questions

(1) Matthew had to pay $4452 in order to furnish the loan taken 3 years before. If the rate of simple interest was 2% then find the sum borrowed.

(2) Find the amount to be paid if Thomas borrowed a sum of $5800 at 3% simple interest for 7 years.

(3) Nancy had to pay $4648 in order to furnish the loan taken 3 years before. If the rate of simple interest was 4% then find the sum borrowed.

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

(5) How much loan did Susan borrow 5 years ago at a rate of simple interest 5% per annum, if he paid $7062.5 to clear it?

(6) What amount does Patricia have to pay after 6 years if he takes a loan of $3150 at 5% simple interest?

(7) Calculate the amount due after 9 years if Barbara borrowed a sum of $5550 at a rate of 5% simple interest.

(8) How much loan did Steven borrow 5 years ago at a rate of simple interest 2% per annum, if he paid $7260 to clear it?

(9) In how much time a principal of $3100 will amount to $3720 at a simple interest of 4% per annum?

(10) Daniel took a loan of $6200 at the rate of 6% simple interest per annum. If he paid an amount of $8432 to clear the loan, then find the time period of the loan.