Simple Interest
Math MCQs

Question :    Find the amount to be paid if Susan borrowed a sum of $5650 at 9% simple interest for 7 years.

Correct Answer  $9209.5

Solution & Explanation

Solution

Given,

Principal (P) = $5650

Rate of Simple Interest (SI) = 9%

Time (t) = 7 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) = $5650 × 9% × 7

= $5650 ×⁹/₁₀₀ × 7

= ^{5650 × 9 × 7}/₁₀₀

= ^{50850 × 7}/₁₀₀

= ³⁵⁵⁹⁵⁰/₁₀₀

= $3559.5

Thus, Simple Interest = $3559.5

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 = $5650 + $3559.5

= $9209.5

Thus, Amount to be paid = $9209.5 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 = $5650

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

And, Time (t) = 7 years

Thus, Amount (A)

= $5650 + ($5650 × 9% × 7)

= $5650 + ($5650 ×⁹/₁₀₀ × 7)

= $5650 + (^{5650 × 9 × 7}/₁₀₀)

= $5650 + (^{50850 × 7}/₁₀₀)

= $5650 + (³⁵⁵⁹⁵⁰/₁₀₀)

= $5650 + $3559.5 = $9209.5

Thus, Amount (A) to be paid = $9209.5 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 $5650, the simple interest in 1 year

= ⁹/₁₀₀ × 5650

= ^{9 × 5650}/₁₀₀

= ⁵⁰⁸⁵⁰/₁₀₀ = $508.5

Thus, simple interest for 1 year = $508.5

Therefore, simple interest for 7 years

= Simple interest for 1 year × 7

= $508.5 × 7 = $3559.5

Thus, Simple Interest (SI) = $3559.5

Calculation of Amount

Amount = Principal + Interest

Thus, Amount = $5650 + $3559.5

= $9209.5

Thus, Amount to be paid = $9209.5 Answer

Similar Questions

(1) Calculate the amount due after 10 years if Elizabeth borrowed a sum of $5450 at a rate of 9% simple interest.

(2) Find the amount to be paid if Thomas borrowed a sum of $5800 at 9% simple interest for 8 years.

(3) Calculate the amount due after 10 years if Elizabeth borrowed a sum of $5450 at a rate of 4% simple interest.

(4) Calculate the amount due if Mary borrowed a sum of $3050 at 7% simple interest for 3 years.

(5) How much loan did Karen borrow 5 years ago at a rate of simple interest 4% per annum, if he paid $7140 to clear it?

(6) Jessica took a loan of $5500 at the rate of 7% simple interest per annum. If he paid an amount of $9350 to clear the loan, then find the time period of the loan.

(7) Calculate the amount due after 9 years if Sarah borrowed a sum of $5850 at a rate of 10% simple interest.

(8) Calculate the amount due if Michael borrowed a sum of $3300 at 9% simple interest for 4 years.

(9) Find the amount to be paid if Jennifer borrowed a sum of $5250 at 9% simple interest for 7 years.

(10) Calculate the amount due if Michael borrowed a sum of $3300 at 5% simple interest for 4 years.