Simple Interest
Math MCQs

Question :    Find the amount to be paid if Christopher borrowed a sum of $6000 at 8% simple interest for 8 years.

Correct Answer  $9840

Solution & Explanation

Solution

Given,

Principal (P) = $6000

Rate of Simple Interest (SI) = 8%

Time (t) = 8 years

Thus, Amount (A) = ?

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

Thus, here 8% simple interest means, Rate of Simple Interest (SI) is 8% 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) = $6000 × 8% × 8

= $6000 ×⁸/₁₀₀ × 8

= ^{6000 × 8 × 8}/₁₀₀

= ^{48000 × 8}/₁₀₀

= ³⁸⁴⁰⁰⁰/₁₀₀

= $3840

Thus, Simple Interest = $3840

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 = $6000 + $3840

= $9840

Thus, Amount to be paid = $9840 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 = $6000

Rate of Simple Interest (SI) or (R) = 8%

And, Time (t) = 8 years

Thus, Amount (A)

= $6000 + ($6000 × 8% × 8)

= $6000 + ($6000 ×⁸/₁₀₀ × 8)

= $6000 + (^{6000 × 8 × 8}/₁₀₀)

= $6000 + (^{48000 × 8}/₁₀₀)

= $6000 + (³⁸⁴⁰⁰⁰/₁₀₀)

= $6000 + $3840 = $9840

Thus, Amount (A) to be paid = $9840 Answer

Method (3) Unitary Method

Calculation of Amount using Unitary Method

Calculation of Interest using Unitary Method

Here, given Rate of Simple Interest = 8%

This, means, $8 per $100 per year

∵ For $100, the simple interest for 1 year = $8

∴ For $1, the simple interest for 1 year = ⁸/₁₀₀

∴ For $6000, the simple interest in 1 year

= ⁸/₁₀₀ × 6000

= ^{8 × 6000}/₁₀₀

= ⁴⁸⁰⁰⁰/₁₀₀ = $480

Thus, simple interest for 1 year = $480

Therefore, simple interest for 8 years

= Simple interest for 1 year × 8

= $480 × 8 = $3840

Thus, Simple Interest (SI) = $3840

Calculation of Amount

Amount = Principal + Interest

Thus, Amount = $6000 + $3840

= $9840

Thus, Amount to be paid = $9840 Answer

Similar Questions

(1) What amount will be due after 2 years if Joseph borrowed a sum of $3350 at a 5% simple interest?

(2) Karen took a loan of $5900 at the rate of 8% simple interest per annum. If he paid an amount of $8732 to clear the loan, then find the time period of the loan.

(3) Charles took a loan of $5800 at the rate of 7% simple interest per annum. If he paid an amount of $9860 to clear the loan, then find the time period of the loan.

(4) Calculate the amount due after 9 years if Patricia borrowed a sum of $5150 at a rate of 4% simple interest.

(5) Mary took a loan of $4100 at the rate of 6% simple interest per annum. If he paid an amount of $5822 to clear the loan, then find the time period of the loan.

(6) Calculate the amount due after 10 years if William borrowed a sum of $5500 at a rate of 5% simple interest.

(7) Find the amount to be paid if Elizabeth borrowed a sum of $5450 at 9% simple interest for 8 years.

(8) Sarah took a loan of $5700 at the rate of 6% simple interest per annum. If he paid an amount of $8436 to clear the loan, then find the time period of the loan.

(9) What amount does David have to pay after 6 years if he takes a loan of $3400 at 3% simple interest?

(10) Find the amount to be paid if Charles borrowed a sum of $5900 at 4% simple interest for 8 years.