Simple Interest
Math MCQs

Question :  ( 1 of 10 )  Calculate the amount due if Patricia borrowed a sum of $3150 at 10% simple interest for 3 years.

Correct Answer  $4095

Solution & Explanation

Solution

Given,

Principal (P) = $3150

Rate of Simple Interest (SI) = 10%

Time (t) = 3 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) = $3150 × 10% × 3

= $3150 ×¹⁰/₁₀₀ × 3

= ^{3150 × 10 × 3}/₁₀₀

= ^{31500 × 3}/₁₀₀

= ⁹⁴⁵⁰⁰/₁₀₀

= $945

Thus, Simple Interest = $945

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 + $945

= $4095

Thus, Amount to be paid = $4095 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) = 10%

And, Time (t) = 3 years

Thus, Amount (A)

= $3150 + ($3150 × 10% × 3)

= $3150 + ($3150 ×¹⁰/₁₀₀ × 3)

= $3150 + (^{3150 × 10 × 3}/₁₀₀)

= $3150 + (^{31500 × 3}/₁₀₀)

= $3150 + (⁹⁴⁵⁰⁰/₁₀₀)

= $3150 + $945 = $4095

Thus, Amount (A) to be paid = $4095 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 $3150, the simple interest in 1 year

= ¹⁰/₁₀₀ × 3150

= ^{10 × 3150}/₁₀₀

= ³¹⁵⁰⁰/₁₀₀ = $315

Thus, simple interest for 1 year = $315

Therefore, simple interest for 3 years

= Simple interest for 1 year × 3

= $315 × 3 = $945

Thus, Simple Interest (SI) = $945

Calculation of Amount

Amount = Principal + Interest

Thus, Amount = $3150 + $945

= $4095

Thus, Amount to be paid = $4095 Answer

Similar Questions

(1) How much loan did Jason borrow 5 years ago at a rate of simple interest 4% per annum, if he paid $9240 to clear it?

(2) What amount will be due after 2 years if Paul borrowed a sum of $3850 at a 9% simple interest?

(3) How much loan did Timothy borrow 5 years ago at a rate of simple interest 3% per annum, if he paid $8510 to clear it?

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

(5) Charles took a loan of $5800 at the rate of 8% simple interest per annum. If he paid an amount of $8584 to clear the loan, then find the time period of the loan.

(6) How much loan did Karen borrow 5 years ago at a rate of simple interest 2% per annum, if he paid $6545 to clear it?

(7) Mark took a loan of $6800 at the rate of 9% simple interest per annum. If he paid an amount of $10472 to clear the loan, then find the time period of the loan.

(8) Thomas took a loan of $5600 at the rate of 6% simple interest per annum. If he paid an amount of $7952 to clear the loan, then find the time period of the loan.

(9) How much loan did Elizabeth borrow 5 years ago at a rate of simple interest 4% per annum, if he paid $6540 to clear it?

(10) Find the amount to be paid if Karen borrowed a sum of $5950 at 9% simple interest for 7 years.