Simple Interest
Math MCQs

Question :    Calculate the amount due if Richard borrowed a sum of $3600 at 8% simple interest for 4 years.

Correct Answer  $4752

Solution & Explanation

Solution

Given,

Principal (P) = $3600

Rate of Simple Interest (SI) = 8%

Time (t) = 4 years

Thus, Amount (A) = ?

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

Thus, here 8% simple interest means, Rate of Simple Interest (SI) is 8% 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 × 8% × 4

= $3600 ×⁸/₁₀₀ × 4

= ^{3600 × 8 × 4}/₁₀₀

= ^{28800 × 4}/₁₀₀

= ¹¹⁵²⁰⁰/₁₀₀

= $1152

Thus, Simple Interest = $1152

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 + $1152

= $4752

Thus, Amount to be paid = $4752 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) = 8%

And, Time (t) = 4 years

Thus, Amount (A)

= $3600 + ($3600 × 8% × 4)

= $3600 + ($3600 ×⁸/₁₀₀ × 4)

= $3600 + (^{3600 × 8 × 4}/₁₀₀)

= $3600 + (^{28800 × 4}/₁₀₀)

= $3600 + (¹¹⁵²⁰⁰/₁₀₀)

= $3600 + $1152 = $4752

Thus, Amount (A) to be paid = $4752 Answer

Method (3) Unitary Method

Calculation of Amount using Unitary Method

Calculation of Interest using Unitary Method

Here, given Rate of Simple Interest = 8%

This, means, $8 per $100 per year

∵ For $100, the simple interest for 1 year = $8

∴ For $1, the simple interest for 1 year = ⁸/₁₀₀

∴ For $3600, the simple interest in 1 year

= ⁸/₁₀₀ × 3600

= ^{8 × 3600}/₁₀₀

= ²⁸⁸⁰⁰/₁₀₀ = $288

Thus, simple interest for 1 year = $288

Therefore, simple interest for 4 years

= Simple interest for 1 year × 4

= $288 × 4 = $1152

Thus, Simple Interest (SI) = $1152

Calculation of Amount

Amount = Principal + Interest

Thus, Amount = $3600 + $1152

= $4752

Thus, Amount to be paid = $4752 Answer

Similar Questions

(1) What amount does Charles have to pay after 5 years if he takes a loan of $3900 at 4% simple interest?

(2) James took a loan of $4000 at the rate of 10% simple interest per annum. If he paid an amount of $6400 to clear the loan, then find the time period of the loan.

(3) Calculate the amount due after 9 years if Jessica borrowed a sum of $5750 at a rate of 8% simple interest.

(4) How much loan did Jennifer borrow 5 years ago at a rate of simple interest 3% per annum, if he paid $6037.5 to clear it?

(5) What amount does Michael have to pay after 5 years if he takes a loan of $3300 at 10% simple interest?

(6) Donald had to pay $5175 in order to furnish the loan taken 3 years before. If the rate of simple interest was 5% then find the sum borrowed.

(7) What amount does James have to pay after 6 years if he takes a loan of $3000 at 4% simple interest?

(8) What amount does David have to pay after 5 years if he takes a loan of $3400 at 7% simple interest?

(9) Calculate the amount due after 9 years if Michael borrowed a sum of $5300 at a rate of 3% simple interest.

(10) What amount will be due after 2 years if Andrew borrowed a sum of $3900 at a 4% simple interest?