Simple Interest
Math MCQs

Question :    If Robert borrowed $3100 from a bank at a rate of 3% simple interest per annum then find the amount to be paid after 2 years.

Correct Answer  $3286

Solution & Explanation

Solution

Given,

Principal (P) = $3100

Rate of Simple Interest (SI) = 3%

Time (t) = 2 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% × 2

= $3100 ׳/₁₀₀ × 2

= ^{3100 × 3 × 2}/₁₀₀

= ^{9300 × 2}/₁₀₀

= ¹⁸⁶⁰⁰/₁₀₀

= $186

Thus, Simple Interest = $186

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 + $186

= $3286

Thus, Amount to be paid = $3286 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) = 2 years

Thus, Amount (A)

= $3100 + ($3100 × 3% × 2)

= $3100 + ($3100 ׳/₁₀₀ × 2)

= $3100 + (^{3100 × 3 × 2}/₁₀₀)

= $3100 + (^{9300 × 2}/₁₀₀)

= $3100 + (¹⁸⁶⁰⁰/₁₀₀)

= $3100 + $186 = $3286

Thus, Amount (A) to be paid = $3286 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 2 years

= Simple interest for 1 year × 2

= $93 × 2 = $186

Thus, Simple Interest (SI) = $186

Calculation of Amount

Amount = Principal + Interest

Thus, Amount = $3100 + $186

= $3286

Thus, Amount to be paid = $3286 Answer

Similar Questions

(1) Find the amount to be paid if Christopher borrowed a sum of $6000 at 6% simple interest for 8 years.

(2) How much loan did Deborah borrow 5 years ago at a rate of simple interest 2% per annum, if he paid $8195 to clear it?

(3) Calculate the amount due if William borrowed a sum of $3500 at 7% simple interest for 3 years.

(4) Calculate the amount due if John borrowed a sum of $3200 at 8% simple interest for 3 years.

(5) Find the amount to be paid if Michael borrowed a sum of $5300 at 3% simple interest for 8 years.

(6) Jessica took a loan of $5500 at the rate of 10% simple interest per annum. If he paid an amount of $11000 to clear the loan, then find the time period of the loan.

(7) David had to pay $3706 in order to furnish the loan taken 3 years before. If the rate of simple interest was 3% then find the sum borrowed.

(8) Mary took a loan of $4100 at the rate of 9% simple interest per annum. If he paid an amount of $7052 to clear the loan, then find the time period of the loan.

(9) If Emily paid $5320 to settle his loan which he had taken 4 years before at a simple interest of 3%, then find the loan taken.

(10) What amount does Mary have to pay after 5 years if he takes a loan of $3050 at 8% simple interest?