Simple Interest
Math MCQs

Question :    Calculate the amount due if Mary borrowed a sum of $3050 at 3% simple interest for 4 years.

Correct Answer  $3416

Solution & Explanation

Solution

Given,

Principal (P) = $3050

Rate of Simple Interest (SI) = 3%

Time (t) = 4 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) = $3050 × 3% × 4

= $3050 ׳/₁₀₀ × 4

= ^{3050 × 3 × 4}/₁₀₀

= ^{9150 × 4}/₁₀₀

= ³⁶⁶⁰⁰/₁₀₀

= $366

Thus, Simple Interest = $366

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 + $366

= $3416

Thus, Amount to be paid = $3416 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) = 3%

And, Time (t) = 4 years

Thus, Amount (A)

= $3050 + ($3050 × 3% × 4)

= $3050 + ($3050 ׳/₁₀₀ × 4)

= $3050 + (^{3050 × 3 × 4}/₁₀₀)

= $3050 + (^{9150 × 4}/₁₀₀)

= $3050 + (³⁶⁶⁰⁰/₁₀₀)

= $3050 + $366 = $3416

Thus, Amount (A) to be paid = $3416 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 $3050, the simple interest in 1 year

= ³/₁₀₀ × 3050

= ^{3 × 3050}/₁₀₀

= ⁹¹⁵⁰/₁₀₀ = $91.5

Thus, simple interest for 1 year = $91.5

Therefore, simple interest for 4 years

= Simple interest for 1 year × 4

= $91.5 × 4 = $366

Thus, Simple Interest (SI) = $366

Calculation of Amount

Amount = Principal + Interest

Thus, Amount = $3050 + $366

= $3416

Thus, Amount to be paid = $3416 Answer

Similar Questions

(1) Calculate the amount due after 9 years if Richard borrowed a sum of $5600 at a rate of 10% simple interest.

(2) Margaret had to pay $4611 in order to furnish the loan taken 3 years before. If the rate of simple interest was 2% then find the sum borrowed.

(3) If Nancy paid $4648 to settle his loan which he had taken 4 years before at a simple interest of 3%, then find the loan taken.

(4) William took a loan of $5000 at the rate of 8% simple interest per annum. If he paid an amount of $8600 to clear the loan, then find the time period of the loan.

(5) How much loan did Edward borrow 5 years ago at a rate of simple interest 3% per annum, if he paid $8740 to clear it?

(6) Susan had to pay $3869 in order to furnish the loan taken 3 years before. If the rate of simple interest was 2% then find the sum borrowed.

(7) What amount does Elizabeth have to pay after 6 years if he takes a loan of $3450 at 2% simple interest?

(8) Find the amount to be paid if John borrowed a sum of $5200 at 2% simple interest for 7 years.

(9) Calculate the amount due if Barbara borrowed a sum of $3550 at 3% simple interest for 4 years.

(10) In how much time a principal of $3200 will amount to $3712 at a simple interest of 4% per annum?