Simple Interest
Math MCQs

Question :    Calculate the amount due if Elizabeth borrowed a sum of $3450 at 8% simple interest for 3 years.

Correct Answer  $4278

Solution & Explanation

Solution

Given,

Principal (P) = $3450

Rate of Simple Interest (SI) = 8%

Time (t) = 3 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) = $3450 × 8% × 3

= $3450 ×⁸/₁₀₀ × 3

= ^{3450 × 8 × 3}/₁₀₀

= ^{27600 × 3}/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) = 8%

And, Time (t) = 3 years

Thus, Amount (A)

= $3450 + ($3450 × 8% × 3)

= $3450 + ($3450 ×⁸/₁₀₀ × 3)

= $3450 + (^{3450 × 8 × 3}/₁₀₀)

= $3450 + (^{27600 × 3}/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 = 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 $3450, the simple interest in 1 year

= ⁸/₁₀₀ × 3450

= ^{8 × 3450}/₁₀₀

= ²⁷⁶⁰⁰/₁₀₀ = $276

Thus, simple interest for 1 year = $276

Therefore, simple interest for 3 years

= Simple interest for 1 year × 3

= $276 × 3 = $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) In how much time a principal of $3200 will amount to $3840 at a simple interest of 4% per annum?

(2) What amount does Barbara have to pay after 5 years if he takes a loan of $3550 at 9% simple interest?

(3) Calculate the amount due if Karen borrowed a sum of $3950 at 5% simple interest for 3 years.

(4) Find the amount to be paid if Elizabeth borrowed a sum of $5450 at 8% simple interest for 7 years.

(5) Calculate the amount due after 9 years if Linda borrowed a sum of $5350 at a rate of 2% simple interest.

(6) What amount will be due after 2 years if Anthony borrowed a sum of $3650 at a 8% simple interest?

(7) What amount does Elizabeth have to pay after 5 years if he takes a loan of $3450 at 4% simple interest?

(8) Susan took a loan of $5300 at the rate of 10% simple interest per annum. If he paid an amount of $10600 to clear the loan, then find the time period of the loan.

(9) Thomas had to pay $4370 in order to furnish the loan taken 3 years before. If the rate of simple interest was 5% then find the sum borrowed.

(10) Anthony took a loan of $6600 at the rate of 10% simple interest per annum. If he paid an amount of $12540 to clear the loan, then find the time period of the loan.