Simple Interest
Math MCQs

Question :    Calculate the amount due if Michael borrowed a sum of $3300 at 5% simple interest for 3 years.

Correct Answer  $3795

Solution & Explanation

Solution

Given,

Principal (P) = $3300

Rate of Simple Interest (SI) = 5%

Time (t) = 3 years

Thus, Amount (A) = ?

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

Thus, here 5% simple interest means, Rate of Simple Interest (SI) is 5% 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) = $3300 × 5% × 3

= $3300 ×⁵/₁₀₀ × 3

= ^{3300 × 5 × 3}/₁₀₀

= ^{16500 × 3}/₁₀₀

= ⁴⁹⁵⁰⁰/₁₀₀

= $495

Thus, Simple Interest = $495

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 = $3300 + $495

= $3795

Thus, Amount to be paid = $3795 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 = $3300

Rate of Simple Interest (SI) or (R) = 5%

And, Time (t) = 3 years

Thus, Amount (A)

= $3300 + ($3300 × 5% × 3)

= $3300 + ($3300 ×⁵/₁₀₀ × 3)

= $3300 + (^{3300 × 5 × 3}/₁₀₀)

= $3300 + (^{16500 × 3}/₁₀₀)

= $3300 + (⁴⁹⁵⁰⁰/₁₀₀)

= $3300 + $495 = $3795

Thus, Amount (A) to be paid = $3795 Answer

Method (3) Unitary Method

Calculation of Amount using Unitary Method

Calculation of Interest using Unitary Method

Here, given Rate of Simple Interest = 5%

This, means, $5 per $100 per year

∵ For $100, the simple interest for 1 year = $5

∴ For $1, the simple interest for 1 year = ⁵/₁₀₀

∴ For $3300, the simple interest in 1 year

= ⁵/₁₀₀ × 3300

= ^{5 × 3300}/₁₀₀

= ¹⁶⁵⁰⁰/₁₀₀ = $165

Thus, simple interest for 1 year = $165

Therefore, simple interest for 3 years

= Simple interest for 1 year × 3

= $165 × 3 = $495

Thus, Simple Interest (SI) = $495

Calculation of Amount

Amount = Principal + Interest

Thus, Amount = $3300 + $495

= $3795

Thus, Amount to be paid = $3795 Answer

Similar Questions

(1) What amount will be due after 2 years if William borrowed a sum of $3250 at a 5% simple interest?

(2) How much loan did Paul borrow 5 years ago at a rate of simple interest 3% per annum, if he paid $7705 to clear it?

(3) Calculate the amount due if Mary borrowed a sum of $3050 at 7% simple interest for 3 years.

(4) What amount does Karen have to pay after 5 years if he takes a loan of $3950 at 6% simple interest?

(5) What amount does Joseph have to pay after 6 years if he takes a loan of $3700 at 6% simple interest?

(6) In how much time a principal of $3150 will amount to $3339 at a simple interest of 2% per annum?

(7) How much loan did Ronald borrow 5 years ago at a rate of simple interest 4% per annum, if he paid $9000 to clear it?

(8) Richard took a loan of $5200 at the rate of 6% simple interest per annum. If he paid an amount of $8320 to clear the loan, then find the time period of the loan.

(9) Linda took a loan of $4700 at the rate of 9% simple interest per annum. If he paid an amount of $8084 to clear the loan, then find the time period of the loan.

(10) How much loan did Dorothy borrow 5 years ago at a rate of simple interest 3% per annum, if he paid $8337.5 to clear it?