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 will be due after 2 years if Mark borrowed a sum of $3700 at a 10% simple interest?

(2) Calculate the amount due after 9 years if Michael borrowed a sum of $5300 at a rate of 6% simple interest.

(3) What amount does Patricia have to pay after 5 years if he takes a loan of $3150 at 4% simple interest?

(4) Calculate the amount due if Karen borrowed a sum of $3950 at 5% simple interest for 4 years.

(5) John took a loan of $4400 at the rate of 9% simple interest per annum. If he paid an amount of $7568 to clear the loan, then find the time period of the loan.

(6) Find the amount to be paid if Christopher borrowed a sum of $6000 at 5% simple interest for 8 years.

(7) Calculate the amount due after 10 years if James borrowed a sum of $5000 at a rate of 7% simple interest.

(8) Find the amount to be paid if Christopher borrowed a sum of $6000 at 9% simple interest for 8 years.

(9) What amount does Robert have to pay after 5 years if he takes a loan of $3100 at 6% simple interest?

(10) What amount does John have to pay after 5 years if he takes a loan of $3200 at 5% simple interest?