Simple Interest
Math MCQs

Question :    If Patricia borrowed $3150 from a bank at a rate of 3% simple interest per annum then find the amount to be paid after 2 years.

Correct Answer  $3339

Solution & Explanation

Solution

Given,

Principal (P) = $3150

Rate of Simple Interest (SI) = 3%

Time (t) = 2 years

Thus, Amount (A) = ?

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

Thus, here 3% simple interest means, Rate of Simple Interest (SI) is 3% 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) = $3150 × 3% × 2

= $3150 ׳/₁₀₀ × 2

= ^{3150 × 3 × 2}/₁₀₀

= ^{9450 × 2}/₁₀₀

= ¹⁸⁹⁰⁰/₁₀₀

= $189

Thus, Simple Interest = $189

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 = $3150 + $189

= $3339

Thus, Amount to be paid = $3339 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 = $3150

Rate of Simple Interest (SI) or (R) = 3%

And, Time (t) = 2 years

Thus, Amount (A)

= $3150 + ($3150 × 3% × 2)

= $3150 + ($3150 ׳/₁₀₀ × 2)

= $3150 + (^{3150 × 3 × 2}/₁₀₀)

= $3150 + (^{9450 × 2}/₁₀₀)

= $3150 + (¹⁸⁹⁰⁰/₁₀₀)

= $3150 + $189 = $3339

Thus, Amount (A) to be paid = $3339 Answer

Method (3) Unitary Method

Calculation of Amount using Unitary Method

Calculation of Interest using Unitary Method

Here, given Rate of Simple Interest = 3%

This, means, $3 per $100 per year

∵ For $100, the simple interest for 1 year = $3

∴ For $1, the simple interest for 1 year = ³/₁₀₀

∴ For $3150, the simple interest in 1 year

= ³/₁₀₀ × 3150

= ^{3 × 3150}/₁₀₀

= ⁹⁴⁵⁰/₁₀₀ = $94.5

Thus, simple interest for 1 year = $94.5

Therefore, simple interest for 2 years

= Simple interest for 1 year × 2

= $94.5 × 2 = $189

Thus, Simple Interest (SI) = $189

Calculation of Amount

Amount = Principal + Interest

Thus, Amount = $3150 + $189

= $3339

Thus, Amount to be paid = $3339 Answer

Similar Questions

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

(2) Calculate the amount due after 9 years if Michael borrowed a sum of $5300 at a rate of 5% simple interest.

(3) Jennifer took a loan of $4500 at the rate of 7% simple interest per annum. If he paid an amount of $7335 to clear the loan, then find the time period of the loan.

(4) Betty took a loan of $6500 at the rate of 9% simple interest per annum. If he paid an amount of $11180 to clear the loan, then find the time period of the loan.

(5) What amount does Christopher have to pay after 6 years if he takes a loan of $4000 at 10% simple interest?

(6) Lisa took a loan of $6100 at the rate of 10% simple interest per annum. If he paid an amount of $11590 to clear the loan, then find the time period of the loan.

(7) Jessica took a loan of $5500 at the rate of 7% simple interest per annum. If he paid an amount of $8965 to clear the loan, then find the time period of the loan.

(8) Calculate the amount due if Elizabeth borrowed a sum of $3450 at 2% simple interest for 3 years.

(9) Richard took a loan of $5200 at the rate of 8% simple interest per annum. If he paid an amount of $8528 to clear the loan, then find the time period of the loan.

(10) Calculate the amount due after 10 years if Mary borrowed a sum of $5050 at a rate of 5% simple interest.