Simple Interest
Math MCQs

Question :    Calculate the amount due after 9 years if David borrowed a sum of $5400 at a rate of 2% simple interest.

Correct Answer  $6372

Solution & Explanation

Solution

Given,

Principal (P) = $5400

Rate of Simple Interest (SI) = 2%

Time (t) = 9 years

Thus, Amount (A) = ?

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

Thus, here 2% simple interest means, Rate of Simple Interest (SI) is 2% 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 × 2% × 9

= $5400 ײ/₁₀₀ × 9

= ^{5400 × 2 × 9}/₁₀₀

= ^{10800 × 9}/₁₀₀

= ⁹⁷²⁰⁰/₁₀₀

= $972

Thus, Simple Interest = $972

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 + $972

= $6372

Thus, Amount to be paid = $6372 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) = 2%

And, Time (t) = 9 years

Thus, Amount (A)

= $5400 + ($5400 × 2% × 9)

= $5400 + ($5400 ײ/₁₀₀ × 9)

= $5400 + (^{5400 × 2 × 9}/₁₀₀)

= $5400 + (^{10800 × 9}/₁₀₀)

= $5400 + (⁹⁷²⁰⁰/₁₀₀)

= $5400 + $972 = $6372

Thus, Amount (A) to be paid = $6372 Answer

Method (3) Unitary Method

Calculation of Amount using Unitary Method

Calculation of Interest using Unitary Method

Here, given Rate of Simple Interest = 2%

This, means, $2 per $100 per year

∵ For $100, the simple interest for 1 year = $2

∴ For $1, the simple interest for 1 year = ²/₁₀₀

∴ For $5400, the simple interest in 1 year

= ²/₁₀₀ × 5400

= ^{2 × 5400}/₁₀₀

= ¹⁰⁸⁰⁰/₁₀₀ = $108

Thus, simple interest for 1 year = $108

Therefore, simple interest for 9 years

= Simple interest for 1 year × 9

= $108 × 9 = $972

Thus, Simple Interest (SI) = $972

Calculation of Amount

Amount = Principal + Interest

Thus, Amount = $5400 + $972

= $6372

Thus, Amount to be paid = $6372 Answer

Similar Questions

(1) Christopher took a loan of $6000 at the rate of 6% simple interest per annum. If he paid an amount of $9600 to clear the loan, then find the time period of the loan.

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

(3) Calculate the amount due if William borrowed a sum of $3500 at 5% simple interest for 4 years.

(4) How much loan did Carol borrow 5 years ago at a rate of simple interest 3% per annum, if he paid $8107.5 to clear it?

(5) Calculate the amount due if Christopher borrowed a sum of $4000 at 3% simple interest for 4 years.

(6) Richard took a loan of $5200 at the rate of 8% simple interest per annum. If he paid an amount of $8944 to clear the loan, then find the time period of the loan.

(7) What amount does William have to pay after 5 years if he takes a loan of $3500 at 4% simple interest?

(8) Daniel took a loan of $6200 at the rate of 9% simple interest per annum. If he paid an amount of $11780 to clear the loan, then find the time period of the loan.

(9) Find the amount to be paid if David borrowed a sum of $5400 at 6% simple interest for 8 years.

(10) Anthony took a loan of $6600 at the rate of 9% simple interest per annum. If he paid an amount of $11352 to clear the loan, then find the time period of the loan.