Simple Interest
Math MCQs

Question :    Calculate the amount due if Elizabeth borrowed a sum of $3450 at 9% simple interest for 4 years.

Correct Answer  $4692

Solution & Explanation

Solution

Given,

Principal (P) = $3450

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) = $3450 × 9% × 4

= $3450 ×⁹/₁₀₀ × 4

= ^{3450 × 9 × 4}/₁₀₀

= ^{31050 × 4}/₁₀₀

= ¹²⁴²⁰⁰/₁₀₀

= $1242

Thus, Simple Interest = $1242

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 = $3450 + $1242

= $4692

Thus, Amount to be paid = $4692 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 = $3450

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

And, Time (t) = 4 years

Thus, Amount (A)

= $3450 + ($3450 × 9% × 4)

= $3450 + ($3450 ×⁹/₁₀₀ × 4)

= $3450 + (^{3450 × 9 × 4}/₁₀₀)

= $3450 + (^{31050 × 4}/₁₀₀)

= $3450 + (¹²⁴²⁰⁰/₁₀₀)

= $3450 + $1242 = $4692

Thus, Amount (A) to be paid = $4692 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 $3450, the simple interest in 1 year

= ⁹/₁₀₀ × 3450

= ^{9 × 3450}/₁₀₀

= ³¹⁰⁵⁰/₁₀₀ = $310.5

Thus, simple interest for 1 year = $310.5

Therefore, simple interest for 4 years

= Simple interest for 1 year × 4

= $310.5 × 4 = $1242

Thus, Simple Interest (SI) = $1242

Calculation of Amount

Amount = Principal + Interest

Thus, Amount = $3450 + $1242

= $4692

Thus, Amount to be paid = $4692 Answer

Similar Questions

(1) Calculate the amount due if Linda borrowed a sum of $3350 at 7% simple interest for 4 years.

(2) Find the amount to be paid if Richard borrowed a sum of $5600 at 8% simple interest for 7 years.

(3) Jessica took a loan of $5500 at the rate of 7% simple interest per annum. If he paid an amount of $7810 to clear the loan, then find the time period of the loan.

(4) Find the amount to be paid if Elizabeth borrowed a sum of $5450 at 2% simple interest for 7 years.

(5) Nancy took a loan of $6300 at the rate of 8% simple interest per annum. If he paid an amount of $10836 to clear the loan, then find the time period of the loan.

(6) What amount will be due after 2 years if Charles borrowed a sum of $3450 at a 9% simple interest?

(7) Susan took a loan of $5300 at the rate of 9% simple interest per annum. If he paid an amount of $9116 to clear the loan, then find the time period of the loan.

(8) Calculate the amount due after 9 years if Karen borrowed a sum of $5950 at a rate of 6% simple interest.

(9) What amount will be due after 2 years if William borrowed a sum of $3250 at a 6% simple interest?

(10) If Susan paid $4088 to settle his loan which he had taken 4 years before at a simple interest of 3%, then find the loan taken.