Simple Interest
Math MCQs

Question :    What amount does James have to pay after 5 years if he takes a loan of $3000 at 9% simple interest?

Correct Answer  $4350

Solution & Explanation

Solution

Given,

Principal (P) = $3000

Rate of Simple Interest (SI) = 9%

Time (t) = 5 years

Thus, Amount (A) = ?

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

Thus, here 9% simple interest means, Rate of Simple Interest (SI) is 9% 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) = $3000 × 9% × 5

= $3000 ×⁹/₁₀₀ × 5

= ^{3000 × 9 × 5}/₁₀₀

= ^{27000 × 5}/₁₀₀

= ¹³⁵⁰⁰⁰/₁₀₀

= $1350

Thus, Simple Interest = $1350

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 = $3000 + $1350

= $4350

Thus, Amount to be paid = $4350 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 = $3000

Rate of Simple Interest (SI) or (R) = 9%

And, Time (t) = 5 years

Thus, Amount (A)

= $3000 + ($3000 × 9% × 5)

= $3000 + ($3000 ×⁹/₁₀₀ × 5)

= $3000 + (^{3000 × 9 × 5}/₁₀₀)

= $3000 + (^{27000 × 5}/₁₀₀)

= $3000 + (¹³⁵⁰⁰⁰/₁₀₀)

= $3000 + $1350 = $4350

Thus, Amount (A) to be paid = $4350 Answer

Method (3) Unitary Method

Calculation of Amount using Unitary Method

Calculation of Interest using Unitary Method

Here, given Rate of Simple Interest = 9%

This, means, $9 per $100 per year

∵ For $100, the simple interest for 1 year = $9

∴ For $1, the simple interest for 1 year = ⁹/₁₀₀

∴ For $3000, the simple interest in 1 year

= ⁹/₁₀₀ × 3000

= ^{9 × 3000}/₁₀₀

= ²⁷⁰⁰⁰/₁₀₀ = $270

Thus, simple interest for 1 year = $270

Therefore, simple interest for 5 years

= Simple interest for 1 year × 5

= $270 × 5 = $1350

Thus, Simple Interest (SI) = $1350

Calculation of Amount

Amount = Principal + Interest

Thus, Amount = $3000 + $1350

= $4350

Thus, Amount to be paid = $4350 Answer

Similar Questions

(1) Find the amount to be paid if Jennifer borrowed a sum of $5250 at 2% simple interest for 8 years.

(2) Find the amount to be paid if William borrowed a sum of $5500 at 10% simple interest for 8 years.

(3) Find the amount to be paid if Karen borrowed a sum of $5950 at 6% simple interest for 8 years.

(4) Calculate the amount due if Karen borrowed a sum of $3950 at 10% simple interest for 4 years.

(5) Calculate the amount due after 9 years if Richard borrowed a sum of $5600 at a rate of 7% simple interest.

(6) Find the amount to be paid if David borrowed a sum of $5400 at 5% simple interest for 8 years.

(7) Joseph had to pay $4033 in order to furnish the loan taken 3 years before. If the rate of simple interest was 3% then find the sum borrowed.

(8) Calculate the amount due after 9 years if Elizabeth borrowed a sum of $5450 at a rate of 6% simple interest.

(9) What amount does Charles have to pay after 5 years if he takes a loan of $3900 at 9% simple interest?

(10) Daniel took a loan of $6200 at the rate of 10% simple interest per annum. If he paid an amount of $11780 to clear the loan, then find the time period of the loan.