Simple Interest
Math MCQs

Question :    Calculate the amount due if Karen borrowed a sum of $3950 at 6% simple interest for 3 years.

Correct Answer  $4661

Solution & Explanation

Solution

Given,

Principal (P) = $3950

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) = $3950 × 6% × 3

= $3950 ×⁶/₁₀₀ × 3

= ^{3950 × 6 × 3}/₁₀₀

= ^{23700 × 3}/₁₀₀

= ⁷¹¹⁰⁰/₁₀₀

= $711

Thus, Simple Interest = $711

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 = $3950 + $711

= $4661

Thus, Amount to be paid = $4661 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 = $3950

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

And, Time (t) = 3 years

Thus, Amount (A)

= $3950 + ($3950 × 6% × 3)

= $3950 + ($3950 ×⁶/₁₀₀ × 3)

= $3950 + (^{3950 × 6 × 3}/₁₀₀)

= $3950 + (^{23700 × 3}/₁₀₀)

= $3950 + (⁷¹¹⁰⁰/₁₀₀)

= $3950 + $711 = $4661

Thus, Amount (A) to be paid = $4661 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 $3950, the simple interest in 1 year

= ⁶/₁₀₀ × 3950

= ^{6 × 3950}/₁₀₀

= ²³⁷⁰⁰/₁₀₀ = $237

Thus, simple interest for 1 year = $237

Therefore, simple interest for 3 years

= Simple interest for 1 year × 3

= $237 × 3 = $711

Thus, Simple Interest (SI) = $711

Calculation of Amount

Amount = Principal + Interest

Thus, Amount = $3950 + $711

= $4661

Thus, Amount to be paid = $4661 Answer

Similar Questions

(1) Susan took a loan of $5300 at the rate of 7% simple interest per annum. If he paid an amount of $8639 to clear the loan, then find the time period of the loan.

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

(3) Calculate the amount due if Thomas borrowed a sum of $3800 at 9% simple interest for 3 years.

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

(5) How much loan did Kevin borrow 5 years ago at a rate of simple interest 3% per annum, if he paid $8165 to clear it?

(6) Find the amount to be paid if Robert borrowed a sum of $5100 at 10% simple interest for 8 years.

(7) How much loan did Elizabeth borrow 5 years ago at a rate of simple interest 5% per annum, if he paid $6812.5 to clear it?

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

(9) Find the amount to be paid if Richard borrowed a sum of $5600 at 3% simple interest for 8 years.

(10) In how much time a principal of $3050 will amount to $3324.5 at a simple interest of 3% per annum?