Simple Interest
Math MCQs

Question :    Calculate the amount due if Robert borrowed a sum of $3100 at 6% simple interest for 3 years.

Correct Answer  $3658

Solution & Explanation

Solution

Given,

Principal (P) = $3100

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) = $3100 × 6% × 3

= $3100 ×⁶/₁₀₀ × 3

= ^{3100 × 6 × 3}/₁₀₀

= ^{18600 × 3}/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) = 6%

And, Time (t) = 3 years

Thus, Amount (A)

= $3100 + ($3100 × 6% × 3)

= $3100 + ($3100 ×⁶/₁₀₀ × 3)

= $3100 + (^{3100 × 6 × 3}/₁₀₀)

= $3100 + (^{18600 × 3}/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 = 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 $3100, the simple interest in 1 year

= ⁶/₁₀₀ × 3100

= ^{6 × 3100}/₁₀₀

= ¹⁸⁶⁰⁰/₁₀₀ = $186

Thus, simple interest for 1 year = $186

Therefore, simple interest for 3 years

= Simple interest for 1 year × 3

= $186 × 3 = $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 Sarah borrowed a sum of $3850 at 9% simple interest for 4 years.

(2) Lisa took a loan of $6100 at the rate of 9% simple interest per annum. If he paid an amount of $11041 to clear the loan, then find the time period of the loan.

(3) Anthony took a loan of $6600 at the rate of 6% simple interest per annum. If he paid an amount of $8976 to clear the loan, then find the time period of the loan.

(4) Calculate the amount due if Richard borrowed a sum of $3600 at 9% simple interest for 4 years.

(5) Margaret took a loan of $6700 at the rate of 10% simple interest per annum. If he paid an amount of $13400 to clear the loan, then find the time period of the loan.

(6) Calculate the amount due if Karen borrowed a sum of $3950 at 3% simple interest for 3 years.

(7) What amount does David have to pay after 5 years if he takes a loan of $3400 at 4% simple interest?

(8) What amount will be due after 2 years if Anthony borrowed a sum of $3650 at a 5% simple interest?

(9) Find the amount to be paid if Mary borrowed a sum of $5050 at 5% simple interest for 8 years.

(10) Joshua had to pay $5488 in order to furnish the loan taken 3 years before. If the rate of simple interest was 4% then find the sum borrowed.