Simple Interest
Math MCQs

Question :    Calculate the amount due if Richard borrowed a sum of $3600 at 9% simple interest for 4 years.

Correct Answer  $4896

Solution & Explanation

Solution

Given,

Principal (P) = $3600

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) = $3600 × 9% × 4

= $3600 ×⁹/₁₀₀ × 4

= ^{3600 × 9 × 4}/₁₀₀

= ^{32400 × 4}/₁₀₀

= ¹²⁹⁶⁰⁰/₁₀₀

= $1296

Thus, Simple Interest = $1296

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 = $3600 + $1296

= $4896

Thus, Amount to be paid = $4896 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 = $3600

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

And, Time (t) = 4 years

Thus, Amount (A)

= $3600 + ($3600 × 9% × 4)

= $3600 + ($3600 ×⁹/₁₀₀ × 4)

= $3600 + (^{3600 × 9 × 4}/₁₀₀)

= $3600 + (^{32400 × 4}/₁₀₀)

= $3600 + (¹²⁹⁶⁰⁰/₁₀₀)

= $3600 + $1296 = $4896

Thus, Amount (A) to be paid = $4896 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 $3600, the simple interest in 1 year

= ⁹/₁₀₀ × 3600

= ^{9 × 3600}/₁₀₀

= ³²⁴⁰⁰/₁₀₀ = $324

Thus, simple interest for 1 year = $324

Therefore, simple interest for 4 years

= Simple interest for 1 year × 4

= $324 × 4 = $1296

Thus, Simple Interest (SI) = $1296

Calculation of Amount

Amount = Principal + Interest

Thus, Amount = $3600 + $1296

= $4896

Thus, Amount to be paid = $4896 Answer

Similar Questions

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

(2) Calculate the amount due if Joseph borrowed a sum of $3700 at 4% simple interest for 4 years.

(3) Calculate the amount due if Richard borrowed a sum of $3600 at 5% simple interest for 3 years.

(4) How much loan did Jennifer borrow 5 years ago at a rate of simple interest 2% per annum, if he paid $5775 to clear it?

(5) William took a loan of $5000 at the rate of 7% simple interest per annum. If he paid an amount of $7450 to clear the loan, then find the time period of the loan.

(6) Calculate the amount due if John borrowed a sum of $3200 at 4% simple interest for 3 years.

(7) What amount does Christopher have to pay after 5 years if he takes a loan of $4000 at 6% simple interest?

(8) 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.

(9) Richard took a loan of $5200 at the rate of 8% simple interest per annum. If he paid an amount of $8112 to clear the loan, then find the time period of the loan.

(10) How much loan did Michael borrow 5 years ago at a rate of simple interest 4% per annum, if he paid $6360 to clear it?