Simple Interest
Math MCQs

Question :    Calculate the amount due if Michael borrowed a sum of $3300 at 10% simple interest for 4 years.

Correct Answer  $4620

Solution & Explanation

Solution

Given,

Principal (P) = $3300

Rate of Simple Interest (SI) = 10%

Time (t) = 4 years

Thus, Amount (A) = ?

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

Thus, here 10% simple interest means, Rate of Simple Interest (SI) is 10% 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 × 10% × 4

= $3300 ×¹⁰/₁₀₀ × 4

= ^{3300 × 10 × 4}/₁₀₀

= ^{33000 × 4}/₁₀₀

= ¹³²⁰⁰⁰/₁₀₀

= $1320

Thus, Simple Interest = $1320

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 + $1320

= $4620

Thus, Amount to be paid = $4620 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) = 10%

And, Time (t) = 4 years

Thus, Amount (A)

= $3300 + ($3300 × 10% × 4)

= $3300 + ($3300 ×¹⁰/₁₀₀ × 4)

= $3300 + (^{3300 × 10 × 4}/₁₀₀)

= $3300 + (^{33000 × 4}/₁₀₀)

= $3300 + (¹³²⁰⁰⁰/₁₀₀)

= $3300 + $1320 = $4620

Thus, Amount (A) to be paid = $4620 Answer

Method (3) Unitary Method

Calculation of Amount using Unitary Method

Calculation of Interest using Unitary Method

Here, given Rate of Simple Interest = 10%

This, means, $10 per $100 per year

∵ For $100, the simple interest for 1 year = $10

∴ For $1, the simple interest for 1 year = ¹⁰/₁₀₀

∴ For $3300, the simple interest in 1 year

= ¹⁰/₁₀₀ × 3300

= ^{10 × 3300}/₁₀₀

= ³³⁰⁰⁰/₁₀₀ = $330

Thus, simple interest for 1 year = $330

Therefore, simple interest for 4 years

= Simple interest for 1 year × 4

= $330 × 4 = $1320

Thus, Simple Interest (SI) = $1320

Calculation of Amount

Amount = Principal + Interest

Thus, Amount = $3300 + $1320

= $4620

Thus, Amount to be paid = $4620 Answer

Similar Questions

(1) Calculate the amount due after 9 years if Susan borrowed a sum of $5650 at a rate of 5% simple interest.

(2) Calculate the amount due if Richard borrowed a sum of $3600 at 8% simple interest for 3 years.

(3) Margaret took a loan of $6700 at the rate of 8% simple interest per annum. If he paid an amount of $10452 to clear the loan, then find the time period of the loan.

(4) What amount will be due after 2 years if Michael borrowed a sum of $3150 at a 6% simple interest?

(5) What amount will be due after 2 years if David borrowed a sum of $3200 at a 8% simple interest?

(6) What amount does Jessica have to pay after 6 years if he takes a loan of $3750 at 5% simple interest?

(7) Jessica took a loan of $5500 at the rate of 10% simple interest per annum. If he paid an amount of $8800 to clear the loan, then find the time period of the loan.

(8) Robert took a loan of $4200 at the rate of 9% simple interest per annum. If he paid an amount of $7602 to clear the loan, then find the time period of the loan.

(9) Mark took a loan of $6800 at the rate of 8% simple interest per annum. If he paid an amount of $11696 to clear the loan, then find the time period of the loan.

(10) In how much time a principal of $3200 will amount to $3392 at a simple interest of 2% per annum?