Simple Interest
Math MCQs

Question :    Calculate the amount due after 10 years if David borrowed a sum of $5400 at a rate of 9% simple interest.

Correct Answer  $10260

Solution & Explanation

Solution

Given,

Principal (P) = $5400

Rate of Simple Interest (SI) = 9%

Time (t) = 10 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) = $5400 × 9% × 10

= $5400 ×⁹/₁₀₀ × 10

= ^{5400 × 9 × 10}/₁₀₀

= ^{48600 × 10}/₁₀₀

= ⁴⁸⁶⁰⁰⁰/₁₀₀

= $4860

Thus, Simple Interest = $4860

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 + $4860

= $10260

Thus, Amount to be paid = $10260 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) = 9%

And, Time (t) = 10 years

Thus, Amount (A)

= $5400 + ($5400 × 9% × 10)

= $5400 + ($5400 ×⁹/₁₀₀ × 10)

= $5400 + (^{5400 × 9 × 10}/₁₀₀)

= $5400 + (^{48600 × 10}/₁₀₀)

= $5400 + (⁴⁸⁶⁰⁰⁰/₁₀₀)

= $5400 + $4860 = $10260

Thus, Amount (A) to be paid = $10260 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 $5400, the simple interest in 1 year

= ⁹/₁₀₀ × 5400

= ^{9 × 5400}/₁₀₀

= ⁴⁸⁶⁰⁰/₁₀₀ = $486

Thus, simple interest for 1 year = $486

Therefore, simple interest for 10 years

= Simple interest for 1 year × 10

= $486 × 10 = $4860

Thus, Simple Interest (SI) = $4860

Calculation of Amount

Amount = Principal + Interest

Thus, Amount = $5400 + $4860

= $10260

Thus, Amount to be paid = $10260 Answer

Similar Questions

(1) Lisa took a loan of $6100 at the rate of 6% simple interest per annum. If he paid an amount of $9028 to clear the loan, then find the time period of the loan.

(2) Calculate the amount due after 9 years if Karen borrowed a sum of $5950 at a rate of 10% simple interest.

(3) What amount does James have to pay after 6 years if he takes a loan of $3000 at 3% simple interest?

(4) Daniel took a loan of $6200 at the rate of 10% simple interest per annum. If he paid an amount of $11160 to clear the loan, then find the time period of the loan.

(5) What amount will be due after 2 years if Paul borrowed a sum of $3850 at a 10% simple interest?

(6) Michael took a loan of $4600 at the rate of 8% simple interest per annum. If he paid an amount of $6808 to clear the loan, then find the time period of the loan.

(7) Joseph took a loan of $5400 at the rate of 7% simple interest per annum. If he paid an amount of $7668 to clear the loan, then find the time period of the loan.

(8) Calculate the amount due after 9 years if James borrowed a sum of $5000 at a rate of 2% simple interest.

(9) What amount does Barbara have to pay after 6 years if he takes a loan of $3550 at 10% simple interest?

(10) What amount will be due after 2 years if James borrowed a sum of $3000 at a 7% simple interest?