Simple Interest
Math MCQs

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

Correct Answer  $3224

Solution & Explanation

Solution

Given,

Principal (P) = $3100

Rate of Simple Interest (SI) = 2%

Time (t) = 2 years

Thus, Amount (A) = ?

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

Thus, here 2% simple interest means, Rate of Simple Interest (SI) is 2% 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 × 2% × 2

= $3100 ײ/₁₀₀ × 2

= ^{3100 × 2 × 2}/₁₀₀

= ^{6200 × 2}/₁₀₀

= ¹²⁴⁰⁰/₁₀₀

= $124

Thus, Simple Interest = $124

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 + $124

= $3224

Thus, Amount to be paid = $3224 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) = 2%

And, Time (t) = 2 years

Thus, Amount (A)

= $3100 + ($3100 × 2% × 2)

= $3100 + ($3100 ײ/₁₀₀ × 2)

= $3100 + (^{3100 × 2 × 2}/₁₀₀)

= $3100 + (^{6200 × 2}/₁₀₀)

= $3100 + (¹²⁴⁰⁰/₁₀₀)

= $3100 + $124 = $3224

Thus, Amount (A) to be paid = $3224 Answer

Method (3) Unitary Method

Calculation of Amount using Unitary Method

Calculation of Interest using Unitary Method

Here, given Rate of Simple Interest = 2%

This, means, $2 per $100 per year

∵ For $100, the simple interest in 1 year = $2

∴ For $1, the simple interest in 1 year = ²/₁₀₀

∴ For $3100, the simple interest in 1 year

= ²/₁₀₀ × 3100

= ^{2 × 3100}/₁₀₀

= ⁶²⁰⁰/₁₀₀ = $62

Thus, simple interest in 1 year = $62

Therefore, simple interest for 2 years

= Simple interest for 1 year × 2

= $62 × 2 = $124

Thus, Simple Interest (SI) = $124

Calculation of Amount

Amount = Principal + Interest

Thus, Amount = $3100 + $124

= $3224

Thus, Amount to be paid = $3224 Answer

Similar Questions

(1) What amount does Richard have to pay after 6 years if he takes a loan of $3600 at 7% simple interest?

(2) If John paid $3712 to settle his loan which he had taken 4 years before at a simple interest of 4%, then find the loan taken.

(3) Christopher took a loan of $6000 at the rate of 6% simple interest per annum. If he paid an amount of $8160 to clear the loan, then find the time period of the loan.

(4) Calculate the amount due if Jennifer borrowed a sum of $3250 at 5% simple interest for 4 years.

(5) Find the amount to be paid if James borrowed a sum of $5000 at 2% simple interest for 8 years.

(6) Find the amount to be paid if Barbara borrowed a sum of $5550 at 4% simple interest for 8 years.

(7) Lisa took a loan of $6100 at the rate of 7% simple interest per annum. If he paid an amount of $9516 to clear the loan, then find the time period of the loan.

(8) What amount will be due after 2 years if Daniel borrowed a sum of $3550 at a 7% simple interest?

(9) Calculate the amount due after 9 years if Barbara borrowed a sum of $5550 at a rate of 9% simple interest.

(10) Susan took a loan of $5300 at the rate of 8% simple interest per annum. If he paid an amount of $9116 to clear the loan, then find the time period of the loan.