Simple Interest
Math MCQs

Question :    Calculate the amount due if Michael borrowed a sum of $3300 at 5% simple interest for 4 years.

Correct Answer  $3960

Solution & Explanation

Solution

Given,

Principal (P) = $3300

Rate of Simple Interest (SI) = 5%

Time (t) = 4 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% × 4

= $3300 ×⁵/₁₀₀ × 4

= ^{3300 × 5 × 4}/₁₀₀

= ^{16500 × 4}/₁₀₀

= ⁶⁶⁰⁰⁰/₁₀₀

= $660

Thus, Simple Interest = $660

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 + $660

= $3960

Thus, Amount to be paid = $3960 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) = 4 years

Thus, Amount (A)

= $3300 + ($3300 × 5% × 4)

= $3300 + ($3300 ×⁵/₁₀₀ × 4)

= $3300 + (^{3300 × 5 × 4}/₁₀₀)

= $3300 + (^{16500 × 4}/₁₀₀)

= $3300 + (⁶⁶⁰⁰⁰/₁₀₀)

= $3300 + $660 = $3960

Thus, Amount (A) to be paid = $3960 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 4 years

= Simple interest for 1 year × 4

= $165 × 4 = $660

Thus, Simple Interest (SI) = $660

Calculation of Amount

Amount = Principal + Interest

Thus, Amount = $3300 + $660

= $3960

Thus, Amount to be paid = $3960 Answer

Similar Questions

(1) Calculate the amount due if Barbara borrowed a sum of $3550 at 9% simple interest for 4 years.

(2) Calculate the amount due after 10 years if Linda borrowed a sum of $5350 at a rate of 10% simple interest.

(3) Calculate the amount due after 9 years if William borrowed a sum of $5500 at a rate of 10% simple interest.

(4) James had to pay $3180 in order to furnish the loan taken 3 years before. If the rate of simple interest was 2% then find the sum borrowed.

(5) Calculate the amount due if Christopher borrowed a sum of $4000 at 2% simple interest for 3 years.

(6) What amount does Elizabeth have to pay after 5 years if he takes a loan of $3450 at 10% simple interest?

(7) How much loan did Deborah borrow 5 years ago at a rate of simple interest 5% per annum, if he paid $9312.5 to clear it?

(8) What amount does Joseph have to pay after 6 years if he takes a loan of $3700 at 7% simple interest?

(9) Calculate the amount due if Jennifer borrowed a sum of $3250 at 10% simple interest for 3 years.

(10) Find the amount to be paid if Thomas borrowed a sum of $5800 at 6% simple interest for 7 years.