Simple Interest
Math MCQs

Question :    Calculate the amount due if James borrowed a sum of $3000 at 3% simple interest for 4 years.

Correct Answer  $3360

Solution & Explanation

Solution

Given,

Principal (P) = $3000

Rate of Simple Interest (SI) = 3%

Time (t) = 4 years

Thus, Amount (A) = ?

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

Thus, here 3% simple interest means, Rate of Simple Interest (SI) is 3% 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 × 3% × 4

= $3000 ׳/₁₀₀ × 4

= ^{3000 × 3 × 4}/₁₀₀

= ^{9000 × 4}/₁₀₀

= ³⁶⁰⁰⁰/₁₀₀

= $360

Thus, Simple Interest = $360

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 + $360

= $3360

Thus, Amount to be paid = $3360 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) = 3%

And, Time (t) = 4 years

Thus, Amount (A)

= $3000 + ($3000 × 3% × 4)

= $3000 + ($3000 ׳/₁₀₀ × 4)

= $3000 + (^{3000 × 3 × 4}/₁₀₀)

= $3000 + (^{9000 × 4}/₁₀₀)

= $3000 + (³⁶⁰⁰⁰/₁₀₀)

= $3000 + $360 = $3360

Thus, Amount (A) to be paid = $3360 Answer

Method (3) Unitary Method

Calculation of Amount using Unitary Method

Calculation of Interest using Unitary Method

Here, given Rate of Simple Interest = 3%

This, means, $3 per $100 per year

∵ For $100, the simple interest for 1 year = $3

∴ For $1, the simple interest for 1 year = ³/₁₀₀

∴ For $3000, the simple interest in 1 year

= ³/₁₀₀ × 3000

= ^{3 × 3000}/₁₀₀

= ⁹⁰⁰⁰/₁₀₀ = $90

Thus, simple interest for 1 year = $90

Therefore, simple interest for 4 years

= Simple interest for 1 year × 4

= $90 × 4 = $360

Thus, Simple Interest (SI) = $360

Calculation of Amount

Amount = Principal + Interest

Thus, Amount = $3000 + $360

= $3360

Thus, Amount to be paid = $3360 Answer

Similar Questions

(1) Linda took a loan of $4700 at the rate of 6% simple interest per annum. If he paid an amount of $6674 to clear the loan, then find the time period of the loan.

(2) Calculate the amount due after 10 years if John borrowed a sum of $5200 at a rate of 7% simple interest.

(3) Calculate the amount due if Thomas borrowed a sum of $3800 at 6% simple interest for 4 years.

(4) What amount will be due after 2 years if Charles borrowed a sum of $3450 at a 4% simple interest?

(5) Calculate the amount due if Charles borrowed a sum of $3900 at 6% simple interest for 4 years.

(6) If Barbara borrowed $3550 from a bank at a rate of 3% simple interest per annum then find the amount to be paid after 2 years.

(7) Calculate the amount due if Charles borrowed a sum of $3900 at 2% simple interest for 3 years.

(8) Calculate the amount due after 10 years if Karen borrowed a sum of $5950 at a rate of 2% simple interest.

(9) What amount does Sarah have to pay after 6 years if he takes a loan of $3850 at 7% simple interest?

(10) How much loan did Timothy borrow 5 years ago at a rate of simple interest 3% per annum, if he paid $8510 to clear it?