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) What amount does Jennifer have to pay after 6 years if he takes a loan of $3250 at 9% simple interest?

(2) What amount does Robert have to pay after 5 years if he takes a loan of $3100 at 3% simple interest?

(3) What amount does Sarah have to pay after 5 years if he takes a loan of $3850 at 10% simple interest?

(4) In how much time a principal of $3000 will amount to $3240 at a simple interest of 2% per annum?

(5) Margaret took a loan of $6700 at the rate of 8% simple interest per annum. If he paid an amount of $9916 to clear the loan, then find the time period of the loan.

(6) What amount does Thomas have to pay after 5 years if he takes a loan of $3800 at 9% simple interest?

(7) How much loan did Joshua borrow 5 years ago at a rate of simple interest 3% per annum, if he paid $7935 to clear it?

(8) Calculate the amount due after 10 years if Sarah borrowed a sum of $5850 at a rate of 6% simple interest.

(9) Patricia took a loan of $4300 at the rate of 10% simple interest per annum. If he paid an amount of $7310 to clear the loan, then find the time period of the loan.

(10) What amount does Robert have to pay after 5 years if he takes a loan of $3100 at 9% simple interest?