Simple Interest
Math MCQs

Question :    Calculate the amount due if David borrowed a sum of $3400 at 4% simple interest for 3 years.

Correct Answer  $3808

Solution & Explanation

Solution

Given,

Principal (P) = $3400

Rate of Simple Interest (SI) = 4%

Time (t) = 3 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) = $3400 × 4% × 3

= $3400 ×⁴/₁₀₀ × 3

= ^{3400 × 4 × 3}/₁₀₀

= ^{13600 × 3}/₁₀₀

= ⁴⁰⁸⁰⁰/₁₀₀

= $408

Thus, Simple Interest = $408

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 = $3400 + $408

= $3808

Thus, Amount to be paid = $3808 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 = $3400

Rate of Simple Interest (SI) or (R) = 4%

And, Time (t) = 3 years

Thus, Amount (A)

= $3400 + ($3400 × 4% × 3)

= $3400 + ($3400 ×⁴/₁₀₀ × 3)

= $3400 + (^{3400 × 4 × 3}/₁₀₀)

= $3400 + (^{13600 × 3}/₁₀₀)

= $3400 + (⁴⁰⁸⁰⁰/₁₀₀)

= $3400 + $408 = $3808

Thus, Amount (A) to be paid = $3808 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 $3400, the simple interest in 1 year

= ⁴/₁₀₀ × 3400

= ^{4 × 3400}/₁₀₀

= ¹³⁶⁰⁰/₁₀₀ = $136

Thus, simple interest for 1 year = $136

Therefore, simple interest for 3 years

= Simple interest for 1 year × 3

= $136 × 3 = $408

Thus, Simple Interest (SI) = $408

Calculation of Amount

Amount = Principal + Interest

Thus, Amount = $3400 + $408

= $3808

Thus, Amount to be paid = $3808 Answer

Similar Questions

(1) What amount will be due after 2 years if David borrowed a sum of $3200 at a 4% simple interest?

(2) Sandra took a loan of $6900 at the rate of 7% simple interest per annum. If he paid an amount of $10281 to clear the loan, then find the time period of the loan.

(3) If Nancy paid $4648 to settle his loan which he had taken 4 years before at a simple interest of 3%, then find the loan taken.

(4) Susan had to pay $3978.5 in order to furnish the loan taken 3 years before. If the rate of simple interest was 3% then find the sum borrowed.

(5) Jennifer took a loan of $4500 at the rate of 7% simple interest per annum. If he paid an amount of $6705 to clear the loan, then find the time period of the loan.

(6) 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.

(7) Matthew took a loan of $6400 at the rate of 10% simple interest per annum. If he paid an amount of $12160 to clear the loan, then find the time period of the loan.

(8) Barbara took a loan of $5100 at the rate of 8% simple interest per annum. If he paid an amount of $8772 to clear the loan, then find the time period of the loan.

(9) Lisa took a loan of $6100 at the rate of 8% simple interest per annum. If he paid an amount of $9516 to clear the loan, then find the time period of the loan.

(10) What amount will be due after 2 years if Thomas borrowed a sum of $3400 at a 9% simple interest?