Simple Interest
Math MCQs

Question :    Find the amount to be paid if Richard borrowed a sum of $5600 at 8% simple interest for 8 years.

Correct Answer  $9184

Solution & Explanation

Solution

Given,

Principal (P) = $5600

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) = $5600 × 8% × 8

= $5600 ×⁸/₁₀₀ × 8

= ^{5600 × 8 × 8}/₁₀₀

= ^{44800 × 8}/₁₀₀

= ³⁵⁸⁴⁰⁰/₁₀₀

= $3584

Thus, Simple Interest = $3584

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 = $5600 + $3584

= $9184

Thus, Amount to be paid = $9184 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 = $5600

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

And, Time (t) = 8 years

Thus, Amount (A)

= $5600 + ($5600 × 8% × 8)

= $5600 + ($5600 ×⁸/₁₀₀ × 8)

= $5600 + (^{5600 × 8 × 8}/₁₀₀)

= $5600 + (^{44800 × 8}/₁₀₀)

= $5600 + (³⁵⁸⁴⁰⁰/₁₀₀)

= $5600 + $3584 = $9184

Thus, Amount (A) to be paid = $9184 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 $5600, the simple interest in 1 year

= ⁸/₁₀₀ × 5600

= ^{8 × 5600}/₁₀₀

= ⁴⁴⁸⁰⁰/₁₀₀ = $448

Thus, simple interest for 1 year = $448

Therefore, simple interest for 8 years

= Simple interest for 1 year × 8

= $448 × 8 = $3584

Thus, Simple Interest (SI) = $3584

Calculation of Amount

Amount = Principal + Interest

Thus, Amount = $5600 + $3584

= $9184

Thus, Amount to be paid = $9184 Answer

Similar Questions

(1) Calculate the amount due if Robert borrowed a sum of $3100 at 6% simple interest for 4 years.

(2) Sarah took a loan of $5700 at the rate of 9% simple interest per annum. If he paid an amount of $9291 to clear the loan, then find the time period of the loan.

(3) How much loan did Sharon borrow 5 years ago at a rate of simple interest 3% per annum, if he paid $8912.5 to clear it?

(4) Sarah took a loan of $5700 at the rate of 9% simple interest per annum. If he paid an amount of $8778 to clear the loan, then find the time period of the loan.

(5) In how much time a principal of $3200 will amount to $3680 at a simple interest of 3% per annum?

(6) Sarah took a loan of $5700 at the rate of 10% simple interest per annum. If he paid an amount of $9690 to clear the loan, then find the time period of the loan.

(7) Calculate the amount due if Joseph borrowed a sum of $3700 at 2% simple interest for 3 years.

(8) Calculate the amount due if Jessica borrowed a sum of $3750 at 8% simple interest for 4 years.

(9) Calculate the amount due if Karen borrowed a sum of $3950 at 8% simple interest for 3 years.

(10) Calculate the amount due if Barbara borrowed a sum of $3550 at 10% simple interest for 3 years.