Simple Interest
Math MCQs

Question :    Calculate the amount due if Mary borrowed a sum of $3050 at 6% simple interest for 3 years.

Correct Answer  $3599

Solution & Explanation

Solution

Given,

Principal (P) = $3050

Rate of Simple Interest (SI) = 6%

Time (t) = 3 years

Thus, Amount (A) = ?

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

Thus, here 6% simple interest means, Rate of Simple Interest (SI) is 6% 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) = $3050 × 6% × 3

= $3050 ×⁶/₁₀₀ × 3

= ^{3050 × 6 × 3}/₁₀₀

= ^{18300 × 3}/₁₀₀

= ⁵⁴⁹⁰⁰/₁₀₀

= $549

Thus, Simple Interest = $549

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 = $3050 + $549

= $3599

Thus, Amount to be paid = $3599 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 = $3050

Rate of Simple Interest (SI) or (R) = 6%

And, Time (t) = 3 years

Thus, Amount (A)

= $3050 + ($3050 × 6% × 3)

= $3050 + ($3050 ×⁶/₁₀₀ × 3)

= $3050 + (^{3050 × 6 × 3}/₁₀₀)

= $3050 + (^{18300 × 3}/₁₀₀)

= $3050 + (⁵⁴⁹⁰⁰/₁₀₀)

= $3050 + $549 = $3599

Thus, Amount (A) to be paid = $3599 Answer

Method (3) Unitary Method

Calculation of Amount using Unitary Method

Calculation of Interest using Unitary Method

Here, given Rate of Simple Interest = 6%

This, means, $6 per $100 per year

∵ For $100, the simple interest for 1 year = $6

∴ For $1, the simple interest for 1 year = ⁶/₁₀₀

∴ For $3050, the simple interest in 1 year

= ⁶/₁₀₀ × 3050

= ^{6 × 3050}/₁₀₀

= ¹⁸³⁰⁰/₁₀₀ = $183

Thus, simple interest for 1 year = $183

Therefore, simple interest for 3 years

= Simple interest for 1 year × 3

= $183 × 3 = $549

Thus, Simple Interest (SI) = $549

Calculation of Amount

Amount = Principal + Interest

Thus, Amount = $3050 + $549

= $3599

Thus, Amount to be paid = $3599 Answer

Similar Questions

(1) In how much time a principal of $3200 will amount to $3520 at a simple interest of 2% per annum?

(2) What amount does David have to pay after 5 years if he takes a loan of $3400 at 6% simple interest?

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

(4) Donald took a loan of $7000 at the rate of 6% simple interest per annum. If he paid an amount of $10780 to clear the loan, then find the time period of the loan.

(5) If William paid $4060 to settle his loan which he had taken 4 years before at a simple interest of 4%, then find the loan taken.

(6) Christopher took a loan of $6000 at the rate of 7% simple interest per annum. If he paid an amount of $9360 to clear the loan, then find the time period of the loan.

(7) Calculate the amount due if Jennifer borrowed a sum of $3250 at 2% simple interest for 4 years.

(8) In how much time a principal of $3150 will amount to $3465 at a simple interest of 2% per annum?

(9) Find the amount to be paid if William borrowed a sum of $5500 at 10% simple interest for 8 years.

(10) Sarah had to pay $4081 in order to furnish the loan taken 3 years before. If the rate of simple interest was 2% then find the sum borrowed.