Simple Interest
Math MCQs

Question :    What amount does Robert have to pay after 6 years if he takes a loan of $3100 at 3% simple interest?

Correct Answer  $3658

Solution & Explanation

Solution

Given,

Principal (P) = $3100

Rate of Simple Interest (SI) = 3%

Time (t) = 6 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) = $3100 × 3% × 6

= $3100 ׳/₁₀₀ × 6

= ^{3100 × 3 × 6}/₁₀₀

= ^{9300 × 6}/₁₀₀

= ⁵⁵⁸⁰⁰/₁₀₀

= $558

Thus, Simple Interest = $558

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 = $3100 + $558

= $3658

Thus, Amount to be paid = $3658 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 = $3100

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

And, Time (t) = 6 years

Thus, Amount (A)

= $3100 + ($3100 × 3% × 6)

= $3100 + ($3100 ׳/₁₀₀ × 6)

= $3100 + (^{3100 × 3 × 6}/₁₀₀)

= $3100 + (^{9300 × 6}/₁₀₀)

= $3100 + (⁵⁵⁸⁰⁰/₁₀₀)

= $3100 + $558 = $3658

Thus, Amount (A) to be paid = $3658 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 $3100, the simple interest in 1 year

= ³/₁₀₀ × 3100

= ^{3 × 3100}/₁₀₀

= ⁹³⁰⁰/₁₀₀ = $93

Thus, simple interest for 1 year = $93

Therefore, simple interest for 6 years

= Simple interest for 1 year × 6

= $93 × 6 = $558

Thus, Simple Interest (SI) = $558

Calculation of Amount

Amount = Principal + Interest

Thus, Amount = $3100 + $558

= $3658

Thus, Amount to be paid = $3658 Answer

Similar Questions

(1) Calculate the amount due if Susan borrowed a sum of $3650 at 5% simple interest for 3 years.

(2) Karen took a loan of $5900 at the rate of 6% simple interest per annum. If he paid an amount of $8732 to clear the loan, then find the time period of the loan.

(3) Susan took a loan of $5300 at the rate of 9% simple interest per annum. If he paid an amount of $10070 to clear the loan, then find the time period of the loan.

(4) Find the amount to be paid if Charles borrowed a sum of $5900 at 4% simple interest for 8 years.

(5) What amount will be due after 2 years if Joseph borrowed a sum of $3350 at a 5% simple interest?

(6) Karen took a loan of $5900 at the rate of 10% simple interest per annum. If he paid an amount of $11800 to clear the loan, then find the time period of the loan.

(7) Michelle had to pay $5395.5 in order to furnish the loan taken 3 years before. If the rate of simple interest was 3% then find the sum borrowed.

(8) If Matthew paid $4704 to settle his loan which he had taken 4 years before at a simple interest of 3%, then find the loan taken.

(9) What amount does Charles have to pay after 6 years if he takes a loan of $3900 at 9% simple interest?

(10) Find the amount to be paid if Richard borrowed a sum of $5600 at 4% simple interest for 7 years.