Simple Interest
Math MCQs

Question :    Calculate the amount due if Barbara borrowed a sum of $3550 at 9% simple interest for 4 years.

Correct Answer  $4828

Solution & Explanation

Solution

Given,

Principal (P) = $3550

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) = $3550 × 9% × 4

= $3550 ×⁹/₁₀₀ × 4

= ^{3550 × 9 × 4}/₁₀₀

= ^{31950 × 4}/₁₀₀

= ¹²⁷⁸⁰⁰/₁₀₀

= $1278

Thus, Simple Interest = $1278

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 = $3550 + $1278

= $4828

Thus, Amount to be paid = $4828 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 = $3550

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

And, Time (t) = 4 years

Thus, Amount (A)

= $3550 + ($3550 × 9% × 4)

= $3550 + ($3550 ×⁹/₁₀₀ × 4)

= $3550 + (^{3550 × 9 × 4}/₁₀₀)

= $3550 + (^{31950 × 4}/₁₀₀)

= $3550 + (¹²⁷⁸⁰⁰/₁₀₀)

= $3550 + $1278 = $4828

Thus, Amount (A) to be paid = $4828 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 $3550, the simple interest in 1 year

= ⁹/₁₀₀ × 3550

= ^{9 × 3550}/₁₀₀

= ³¹⁹⁵⁰/₁₀₀ = $319.5

Thus, simple interest for 1 year = $319.5

Therefore, simple interest for 4 years

= Simple interest for 1 year × 4

= $319.5 × 4 = $1278

Thus, Simple Interest (SI) = $1278

Calculation of Amount

Amount = Principal + Interest

Thus, Amount = $3550 + $1278

= $4828

Thus, Amount to be paid = $4828 Answer

Similar Questions

(1) Calculate the amount due if James borrowed a sum of $3000 at 9% simple interest for 3 years.

(2) If Andrew paid $5568 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 2% simple interest for 4 years.

(4) Find the amount to be paid if David borrowed a sum of $5400 at 2% simple interest for 8 years.

(5) Calculate the amount due after 9 years if Thomas borrowed a sum of $5800 at a rate of 2% simple interest.

(6) Sarah took a loan of $5700 at the rate of 8% simple interest per annum. If he paid an amount of $9348 to clear the loan, then find the time period of the loan.

(7) Calculate the amount due if Karen borrowed a sum of $3950 at 7% simple interest for 3 years.

(8) If Susan borrowed $3650 from a bank at a rate of 2% simple interest per annum then find the amount to be paid after 2 years.

(9) Calculate the amount due if Sarah borrowed a sum of $3850 at 4% simple interest for 3 years.

(10) Thomas took a loan of $5600 at the rate of 6% simple interest per annum. If he paid an amount of $8960 to clear the loan, then find the time period of the loan.