Simple Interest
Math MCQs

Question :    Calculate the amount due if James borrowed a sum of $3000 at 9% simple interest for 3 years.

Correct Answer  $3810

Solution & Explanation

Solution

Given,

Principal (P) = $3000

Rate of Simple Interest (SI) = 9%

Time (t) = 3 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% × 3

= $3000 ×⁹/₁₀₀ × 3

= ^{3000 × 9 × 3}/₁₀₀

= ^{27000 × 3}/₁₀₀

= ⁸¹⁰⁰⁰/₁₀₀

= $810

Thus, Simple Interest = $810

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 + $810

= $3810

Thus, Amount to be paid = $3810 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) = 3 years

Thus, Amount (A)

= $3000 + ($3000 × 9% × 3)

= $3000 + ($3000 ×⁹/₁₀₀ × 3)

= $3000 + (^{3000 × 9 × 3}/₁₀₀)

= $3000 + (^{27000 × 3}/₁₀₀)

= $3000 + (⁸¹⁰⁰⁰/₁₀₀)

= $3000 + $810 = $3810

Thus, Amount (A) to be paid = $3810 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 3 years

= Simple interest for 1 year × 3

= $270 × 3 = $810

Thus, Simple Interest (SI) = $810

Calculation of Amount

Amount = Principal + Interest

Thus, Amount = $3000 + $810

= $3810

Thus, Amount to be paid = $3810 Answer

Similar Questions

(1) James took a loan of $4000 at the rate of 8% simple interest per annum. If he paid an amount of $6240 to clear the loan, then find the time period of the loan.

(2) Calculate the amount due after 10 years if Joseph borrowed a sum of $5700 at a rate of 6% simple interest.

(3) Mary took a loan of $4100 at the rate of 7% simple interest per annum. If he paid an amount of $6683 to clear the loan, then find the time period of the loan.

(4) Thomas took a loan of $5600 at the rate of 6% simple interest per annum. If he paid an amount of $7616 to clear the loan, then find the time period of the loan.

(5) Calculate the amount due after 9 years if Karen borrowed a sum of $5950 at a rate of 9% simple interest.

(6) Find the amount to be paid if John borrowed a sum of $5200 at 5% simple interest for 8 years.

(7) What amount will be due after 2 years if Joseph borrowed a sum of $3350 at a 10% simple interest?

(8) What amount will be due after 2 years if Matthew borrowed a sum of $3600 at a 6% simple interest?

(9) If Christopher paid $4800 to settle his loan which he had taken 4 years before at a simple interest of 5%, then find the loan taken.

(10) Calculate the amount due after 9 years if Richard borrowed a sum of $5600 at a rate of 8% simple interest.