Simple Interest
Math MCQs

Question :    Calculate the amount due after 9 years if David borrowed a sum of $5400 at a rate of 7% simple interest.

Correct Answer  $8802

Solution & Explanation

Solution

Given,

Principal (P) = $5400

Rate of Simple Interest (SI) = 7%

Time (t) = 9 years

Thus, Amount (A) = ?

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

Thus, here 7% simple interest means, Rate of Simple Interest (SI) is 7% 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) = $5400 × 7% × 9

= $5400 ×⁷/₁₀₀ × 9

= ^{5400 × 7 × 9}/₁₀₀

= ^{37800 × 9}/₁₀₀

= ³⁴⁰²⁰⁰/₁₀₀

= $3402

Thus, Simple Interest = $3402

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 = $5400 + $3402

= $8802

Thus, Amount to be paid = $8802 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 = $5400

Rate of Simple Interest (SI) or (R) = 7%

And, Time (t) = 9 years

Thus, Amount (A)

= $5400 + ($5400 × 7% × 9)

= $5400 + ($5400 ×⁷/₁₀₀ × 9)

= $5400 + (^{5400 × 7 × 9}/₁₀₀)

= $5400 + (^{37800 × 9}/₁₀₀)

= $5400 + (³⁴⁰²⁰⁰/₁₀₀)

= $5400 + $3402 = $8802

Thus, Amount (A) to be paid = $8802 Answer

Method (3) Unitary Method

Calculation of Amount using Unitary Method

Calculation of Interest using Unitary Method

Here, given Rate of Simple Interest = 7%

This, means, $7 per $100 per year

∵ For $100, the simple interest for 1 year = $7

∴ For $1, the simple interest for 1 year = ⁷/₁₀₀

∴ For $5400, the simple interest in 1 year

= ⁷/₁₀₀ × 5400

= ^{7 × 5400}/₁₀₀

= ³⁷⁸⁰⁰/₁₀₀ = $378

Thus, simple interest for 1 year = $378

Therefore, simple interest for 9 years

= Simple interest for 1 year × 9

= $378 × 9 = $3402

Thus, Simple Interest (SI) = $3402

Calculation of Amount

Amount = Principal + Interest

Thus, Amount = $5400 + $3402

= $8802

Thus, Amount to be paid = $8802 Answer

Similar Questions

(1) Michael took a loan of $4600 at the rate of 9% simple interest per annum. If he paid an amount of $7912 to clear the loan, then find the time period of the loan.

(2) Betty took a loan of $6500 at the rate of 6% simple interest per annum. If he paid an amount of $9230 to clear the loan, then find the time period of the loan.

(3) Calculate the amount due after 9 years if Mary borrowed a sum of $5050 at a rate of 8% simple interest.

(4) Find the amount to be paid if Karen borrowed a sum of $5950 at 9% simple interest for 7 years.

(5) What amount does Joseph have to pay after 6 years if he takes a loan of $3700 at 3% simple interest?

(6) Margaret took a loan of $6700 at the rate of 9% simple interest per annum. If he paid an amount of $12127 to clear the loan, then find the time period of the loan.

(7) Find the amount to be paid if Christopher borrowed a sum of $6000 at 7% simple interest for 8 years.

(8) If Linda paid $3752 to settle his loan which he had taken 4 years before at a simple interest of 3%, then find the loan taken.

(9) In how much time a principal of $3050 will amount to $3538 at a simple interest of 4% per annum?

(10) What amount will be due after 2 years if John borrowed a sum of $3100 at a 7% simple interest?