Simple Interest
Math MCQs

Question :    What amount will be due after 2 years if Christopher borrowed a sum of $3500 at a 10% simple interest?

Correct Answer  $4200

Solution & Explanation

Solution

Given,

Principal (P) = $3500

Rate of Simple Interest (SI) = 10%

Time (t) = 2 years

Thus, Amount (A) = ?

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

Thus, here 10% simple interest means, Rate of Simple Interest (SI) is 10% 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) = $3500 × 10% × 2

= $3500 ×¹⁰/₁₀₀ × 2

= ^{3500 × 10 × 2}/₁₀₀

= ^{35000 × 2}/₁₀₀

= ⁷⁰⁰⁰⁰/₁₀₀

= $700

Thus, Simple Interest = $700

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 = $3500 + $700

= $4200

Thus, Amount to be paid = $4200 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 = $3500

Rate of Simple Interest (SI) or (R) = 10%

And, Time (t) = 2 years

Thus, Amount (A)

= $3500 + ($3500 × 10% × 2)

= $3500 + ($3500 ×¹⁰/₁₀₀ × 2)

= $3500 + (^{3500 × 10 × 2}/₁₀₀)

= $3500 + (^{35000 × 2}/₁₀₀)

= $3500 + (⁷⁰⁰⁰⁰/₁₀₀)

= $3500 + $700 = $4200

Thus, Amount (A) to be paid = $4200 Answer

Method (3) Unitary Method

Calculation of Amount using Unitary Method

Calculation of Interest using Unitary Method

Here, given Rate of Simple Interest = 10%

This, means, $10 per $100 per year

∵ For $100, the simple interest for 1 year = $10

∴ For $1, the simple interest for 1 year = ¹⁰/₁₀₀

∴ For $3500, the simple interest in 1 year

= ¹⁰/₁₀₀ × 3500

= ^{10 × 3500}/₁₀₀

= ³⁵⁰⁰⁰/₁₀₀ = $350

Thus, simple interest for 1 year = $350

Therefore, simple interest for 2 years

= Simple interest for 1 year × 2

= $350 × 2 = $700

Thus, Simple Interest (SI) = $700

Calculation of Amount

Amount = Principal + Interest

Thus, Amount = $3500 + $700

= $4200

Thus, Amount to be paid = $4200 Answer

Similar Questions

(1) Calculate the amount due after 10 years if Charles borrowed a sum of $5900 at a rate of 4% simple interest.

(2) In how much time a principal of $3100 will amount to $3596 at a simple interest of 4% per annum?

(3) Margaret took a loan of $6700 at the rate of 10% simple interest per annum. If he paid an amount of $13400 to clear the loan, then find the time period of the loan.

(4) Donald took a loan of $7000 at the rate of 6% simple interest per annum. If he paid an amount of $9940 to clear the loan, then find the time period of the loan.

(5) Patricia took a loan of $4300 at the rate of 9% simple interest per annum. If he paid an amount of $7009 to clear the loan, then find the time period of the loan.

(6) What amount does Susan have to pay after 5 years if he takes a loan of $3650 at 9% simple interest?

(7) Calculate the amount due after 10 years if David borrowed a sum of $5400 at a rate of 3% simple interest.

(8) Calculate the amount due after 10 years if Christopher borrowed a sum of $6000 at a rate of 5% simple interest.

(9) What amount does Robert have to pay after 5 years if he takes a loan of $3100 at 9% simple interest?

(10) Find the amount to be paid if Elizabeth borrowed a sum of $5450 at 10% simple interest for 7 years.