Simple Interest
Math MCQs

Question :    Calculate the amount due if Thomas borrowed a sum of $3800 at 9% simple interest for 4 years.

Correct Answer  $5168

Solution & Explanation

Solution

Given,

Principal (P) = $3800

Rate of Simple Interest (SI) = 9%

Time (t) = 4 years

Thus, Amount (A) = ?

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

Thus, here 9% simple interest means, Rate of Simple Interest (SI) is 9% 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) = $3800 × 9% × 4

= $3800 ×⁹/₁₀₀ × 4

= ^{3800 × 9 × 4}/₁₀₀

= ^{34200 × 4}/₁₀₀

= ¹³⁶⁸⁰⁰/₁₀₀

= $1368

Thus, Simple Interest = $1368

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 = $3800 + $1368

= $5168

Thus, Amount to be paid = $5168 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 = $3800

Rate of Simple Interest (SI) or (R) = 9%

And, Time (t) = 4 years

Thus, Amount (A)

= $3800 + ($3800 × 9% × 4)

= $3800 + ($3800 ×⁹/₁₀₀ × 4)

= $3800 + (^{3800 × 9 × 4}/₁₀₀)

= $3800 + (^{34200 × 4}/₁₀₀)

= $3800 + (¹³⁶⁸⁰⁰/₁₀₀)

= $3800 + $1368 = $5168

Thus, Amount (A) to be paid = $5168 Answer

Method (3) Unitary Method

Calculation of Amount using Unitary Method

Calculation of Interest using Unitary Method

Here, given Rate of Simple Interest = 9%

This, means, $9 per $100 per year

∵ For $100, the simple interest for 1 year = $9

∴ For $1, the simple interest for 1 year = ⁹/₁₀₀

∴ For $3800, the simple interest in 1 year

= ⁹/₁₀₀ × 3800

= ^{9 × 3800}/₁₀₀

= ³⁴²⁰⁰/₁₀₀ = $342

Thus, simple interest for 1 year = $342

Therefore, simple interest for 4 years

= Simple interest for 1 year × 4

= $342 × 4 = $1368

Thus, Simple Interest (SI) = $1368

Calculation of Amount

Amount = Principal + Interest

Thus, Amount = $3800 + $1368

= $5168

Thus, Amount to be paid = $5168 Answer

Similar Questions

(1) Thomas took a loan of $5600 at the rate of 7% simple interest per annum. If he paid an amount of $8344 to clear the loan, then find the time period of the loan.

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

(3) Calculate the amount due if Christopher borrowed a sum of $4000 at 2% simple interest for 3 years.

(4) How much loan did Ryan borrow 5 years ago at a rate of simple interest 5% per annum, if he paid $9875 to clear it?

(5) Paul had to pay $5405 in order to furnish the loan taken 3 years before. If the rate of simple interest was 5% then find the sum borrowed.

(6) Sandra took a loan of $6900 at the rate of 9% simple interest per annum. If he paid an amount of $13110 to clear the loan, then find the time period of the loan.

(7) Thomas had to pay $4256 in order to furnish the loan taken 3 years before. If the rate of simple interest was 4% then find the sum borrowed.

(8) Find the amount to be paid if Mary borrowed a sum of $5050 at 2% simple interest for 8 years.

(9) Calculate the amount due if Linda borrowed a sum of $3350 at 3% simple interest for 4 years.

(10) Christopher took a loan of $6000 at the rate of 9% simple interest per annum. If he paid an amount of $10860 to clear the loan, then find the time period of the loan.