Simple Interest
Math MCQs

Question :    What amount will be due after 2 years if Andrew borrowed a sum of $3900 at a 6% simple interest?

Correct Answer  $4368

Solution & Explanation

Solution

Given,

Principal (P) = $3900

Rate of Simple Interest (SI) = 6%

Time (t) = 2 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) = $3900 × 6% × 2

= $3900 ×⁶/₁₀₀ × 2

= ^{3900 × 6 × 2}/₁₀₀

= ^{23400 × 2}/₁₀₀

= ⁴⁶⁸⁰⁰/₁₀₀

= $468

Thus, Simple Interest = $468

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 = $3900 + $468

= $4368

Thus, Amount to be paid = $4368 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 = $3900

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

And, Time (t) = 2 years

Thus, Amount (A)

= $3900 + ($3900 × 6% × 2)

= $3900 + ($3900 ×⁶/₁₀₀ × 2)

= $3900 + (^{3900 × 6 × 2}/₁₀₀)

= $3900 + (^{23400 × 2}/₁₀₀)

= $3900 + (⁴⁶⁸⁰⁰/₁₀₀)

= $3900 + $468 = $4368

Thus, Amount (A) to be paid = $4368 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 $3900, the simple interest in 1 year

= ⁶/₁₀₀ × 3900

= ^{6 × 3900}/₁₀₀

= ²³⁴⁰⁰/₁₀₀ = $234

Thus, simple interest for 1 year = $234

Therefore, simple interest for 2 years

= Simple interest for 1 year × 2

= $234 × 2 = $468

Thus, Simple Interest (SI) = $468

Calculation of Amount

Amount = Principal + Interest

Thus, Amount = $3900 + $468

= $4368

Thus, Amount to be paid = $4368 Answer

Similar Questions

(1) Find the amount to be paid if Karen borrowed a sum of $5950 at 6% simple interest for 7 years.

(2) Calculate the amount due after 9 years if Robert borrowed a sum of $5100 at a rate of 5% simple interest.

(3) What amount does Susan have to pay after 5 years if he takes a loan of $3650 at 2% simple interest?

(4) If Christopher borrowed $4000 from a bank at a rate of 2% simple interest per annum then find the amount to be paid after 2 years.

(5) Calculate the amount due if James borrowed a sum of $3000 at 5% simple interest for 3 years.

(6) Find the amount to be paid if Barbara borrowed a sum of $5550 at 6% simple interest for 8 years.

(7) Andrew had to pay $5232 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 10 years if Sarah borrowed a sum of $5850 at a rate of 9% simple interest.

(9) What amount does David have to pay after 6 years if he takes a loan of $3400 at 9% simple interest?

(10) If Mark paid $5104 to settle his loan which he had taken 4 years before at a simple interest of 4%, then find the loan taken.