Simple Interest
Math MCQs

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

Correct Answer  $4216

Solution & Explanation

Solution

Given,

Principal (P) = $3100

Rate of Simple Interest (SI) = 6%

Time (t) = 6 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% × 6

= $3100 ×⁶/₁₀₀ × 6

= ^{3100 × 6 × 6}/₁₀₀

= ^{18600 × 6}/₁₀₀

= ¹¹¹⁶⁰⁰/₁₀₀

= $1116

Thus, Simple Interest = $1116

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 + $1116

= $4216

Thus, Amount to be paid = $4216 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) = 6 years

Thus, Amount (A)

= $3100 + ($3100 × 6% × 6)

= $3100 + ($3100 ×⁶/₁₀₀ × 6)

= $3100 + (^{3100 × 6 × 6}/₁₀₀)

= $3100 + (^{18600 × 6}/₁₀₀)

= $3100 + (¹¹¹⁶⁰⁰/₁₀₀)

= $3100 + $1116 = $4216

Thus, Amount (A) to be paid = $4216 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 6 years

= Simple interest for 1 year × 6

= $186 × 6 = $1116

Thus, Simple Interest (SI) = $1116

Calculation of Amount

Amount = Principal + Interest

Thus, Amount = $3100 + $1116

= $4216

Thus, Amount to be paid = $4216 Answer

Similar Questions

(1) Calculate the amount due after 10 years if Charles borrowed a sum of $5900 at a rate of 3% simple interest.

(2) Calculate the amount due if Mary borrowed a sum of $3050 at 8% simple interest for 3 years.

(3) Calculate the amount due if Patricia borrowed a sum of $3150 at 8% simple interest for 4 years.

(4) Mark took a loan of $6800 at the rate of 7% simple interest per annum. If he paid an amount of $11084 to clear the loan, then find the time period of the loan.

(5) How much loan did Dorothy borrow 5 years ago at a rate of simple interest 5% per annum, if he paid $9062.5 to clear it?

(6) Jessica took a loan of $5500 at the rate of 7% simple interest per annum. If he paid an amount of $9350 to clear the loan, then find the time period of the loan.

(7) How much loan did Ronald borrow 5 years ago at a rate of simple interest 2% per annum, if he paid $8250 to clear it?

(8) Calculate the amount due if Joseph borrowed a sum of $3700 at 2% simple interest for 4 years.

(9) If Sandra paid $4806 to settle his loan which he had taken 4 years before at a simple interest of 2%, then find the loan taken.

(10) Nancy took a loan of $6300 at the rate of 7% simple interest per annum. If he paid an amount of $10710 to clear the loan, then find the time period of the loan.