Simple Interest
Math MCQs

Question :    Calculate the amount due if John borrowed a sum of $3200 at 8% simple interest for 3 years.

Correct Answer  $3968

Solution & Explanation

Solution

Given,

Principal (P) = $3200

Rate of Simple Interest (SI) = 8%

Time (t) = 3 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) = $3200 × 8% × 3

= $3200 ×⁸/₁₀₀ × 3

= ^{3200 × 8 × 3}/₁₀₀

= ^{25600 × 3}/₁₀₀

= ⁷⁶⁸⁰⁰/₁₀₀

= $768

Thus, Simple Interest = $768

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 = $3200 + $768

= $3968

Thus, Amount to be paid = $3968 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 = $3200

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

And, Time (t) = 3 years

Thus, Amount (A)

= $3200 + ($3200 × 8% × 3)

= $3200 + ($3200 ×⁸/₁₀₀ × 3)

= $3200 + (^{3200 × 8 × 3}/₁₀₀)

= $3200 + (^{25600 × 3}/₁₀₀)

= $3200 + (⁷⁶⁸⁰⁰/₁₀₀)

= $3200 + $768 = $3968

Thus, Amount (A) to be paid = $3968 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 $3200, the simple interest in 1 year

= ⁸/₁₀₀ × 3200

= ^{8 × 3200}/₁₀₀

= ²⁵⁶⁰⁰/₁₀₀ = $256

Thus, simple interest for 1 year = $256

Therefore, simple interest for 3 years

= Simple interest for 1 year × 3

= $256 × 3 = $768

Thus, Simple Interest (SI) = $768

Calculation of Amount

Amount = Principal + Interest

Thus, Amount = $3200 + $768

= $3968

Thus, Amount to be paid = $3968 Answer

Similar Questions

(1) Find the amount to be paid if Linda borrowed a sum of $5350 at 8% simple interest for 7 years.

(2) Find the amount to be paid if Joseph borrowed a sum of $5700 at 7% simple interest for 8 years.

(3) Mark took a loan of $6800 at the rate of 8% simple interest per annum. If he paid an amount of $11696 to clear the loan, then find the time period of the loan.

(4) Susan took a loan of $5300 at the rate of 9% simple interest per annum. If he paid an amount of $8639 to clear the loan, then find the time period of the loan.

(5) What amount does John have to pay after 5 years if he takes a loan of $3200 at 9% simple interest?

(6) Calculate the amount due if James borrowed a sum of $3000 at 9% simple interest for 4 years.

(7) Calculate the amount due if Elizabeth borrowed a sum of $3450 at 10% simple interest for 3 years.

(8) What amount does James have to pay after 6 years if he takes a loan of $3000 at 4% simple interest?

(9) If Robert paid $3596 to settle his loan which he had taken 4 years before at a simple interest of 4%, then find the loan taken.

(10) If Mark paid $4928 to settle his loan which he had taken 4 years before at a simple interest of 3%, then find the loan taken.