Simple Interest
Math MCQs

Question :    Calculate the amount due if John borrowed a sum of $3200 at 4% simple interest for 4 years.

Correct Answer  $3712

Solution & Explanation

Solution

Given,

Principal (P) = $3200

Rate of Simple Interest (SI) = 4%

Time (t) = 4 years

Thus, Amount (A) = ?

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

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

= $3200 ×⁴/₁₀₀ × 4

= ^{3200 × 4 × 4}/₁₀₀

= ^{12800 × 4}/₁₀₀

= ⁵¹²⁰⁰/₁₀₀

= $512

Thus, Simple Interest = $512

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 + $512

= $3712

Thus, Amount to be paid = $3712 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) = 4%

And, Time (t) = 4 years

Thus, Amount (A)

= $3200 + ($3200 × 4% × 4)

= $3200 + ($3200 ×⁴/₁₀₀ × 4)

= $3200 + (^{3200 × 4 × 4}/₁₀₀)

= $3200 + (^{12800 × 4}/₁₀₀)

= $3200 + (⁵¹²⁰⁰/₁₀₀)

= $3200 + $512 = $3712

Thus, Amount (A) to be paid = $3712 Answer

Method (3) Unitary Method

Calculation of Amount using Unitary Method

Calculation of Interest using Unitary Method

Here, given Rate of Simple Interest = 4%

This, means, $4 per $100 per year

∵ For $100, the simple interest for 1 year = $4

∴ For $1, the simple interest for 1 year = ⁴/₁₀₀

∴ For $3200, the simple interest in 1 year

= ⁴/₁₀₀ × 3200

= ^{4 × 3200}/₁₀₀

= ¹²⁸⁰⁰/₁₀₀ = $128

Thus, simple interest for 1 year = $128

Therefore, simple interest for 4 years

= Simple interest for 1 year × 4

= $128 × 4 = $512

Thus, Simple Interest (SI) = $512

Calculation of Amount

Amount = Principal + Interest

Thus, Amount = $3200 + $512

= $3712

Thus, Amount to be paid = $3712 Answer

Similar Questions

(1) Calculate the amount due after 9 years if Jessica borrowed a sum of $5750 at a rate of 6% simple interest.

(2) If Margaret paid $5046 to settle his loan which he had taken 4 years before at a simple interest of 4%, then find the loan taken.

(3) Calculate the amount due if Charles borrowed a sum of $3900 at 8% simple interest for 4 years.

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

(5) Find the amount to be paid if William borrowed a sum of $5500 at 4% simple interest for 7 years.

(6) In how much time a principal of $3150 will amount to $3402 at a simple interest of 4% per annum?

(7) John took a loan of $4400 at the rate of 7% simple interest per annum. If he paid an amount of $6248 to clear the loan, then find the time period of the loan.

(8) Calculate the amount due if William borrowed a sum of $3500 at 3% simple interest for 3 years.

(9) Joseph took a loan of $5400 at the rate of 9% simple interest per annum. If he paid an amount of $9288 to clear the loan, then find the time period of the loan.

(10) How much loan did David borrow 5 years ago at a rate of simple interest 2% per annum, if he paid $5940 to clear it?