Simple Interest
Math MCQs

Question :    Find the amount to be paid if Robert borrowed a sum of $5100 at 2% simple interest for 8 years.

Correct Answer  $5916

Solution & Explanation

Solution

Given,

Principal (P) = $5100

Rate of Simple Interest (SI) = 2%

Time (t) = 8 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) = $5100 × 2% × 8

= $5100 ײ/₁₀₀ × 8

= ^{5100 × 2 × 8}/₁₀₀

= ^{10200 × 8}/₁₀₀

= ⁸¹⁶⁰⁰/₁₀₀

= $816

Thus, Simple Interest = $816

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 = $5100 + $816

= $5916

Thus, Amount to be paid = $5916 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 = $5100

Rate of Simple Interest (SI) or (R) = 2%

And, Time (t) = 8 years

Thus, Amount (A)

= $5100 + ($5100 × 2% × 8)

= $5100 + ($5100 ײ/₁₀₀ × 8)

= $5100 + (^{5100 × 2 × 8}/₁₀₀)

= $5100 + (^{10200 × 8}/₁₀₀)

= $5100 + (⁸¹⁶⁰⁰/₁₀₀)

= $5100 + $816 = $5916

Thus, Amount (A) to be paid = $5916 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 for 1 year = $2

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

∴ For $5100, the simple interest in 1 year

= ²/₁₀₀ × 5100

= ^{2 × 5100}/₁₀₀

= ¹⁰²⁰⁰/₁₀₀ = $102

Thus, simple interest for 1 year = $102

Therefore, simple interest for 8 years

= Simple interest for 1 year × 8

= $102 × 8 = $816

Thus, Simple Interest (SI) = $816

Calculation of Amount

Amount = Principal + Interest

Thus, Amount = $5100 + $816

= $5916

Thus, Amount to be paid = $5916 Answer

Similar Questions

(1) James took a loan of $4000 at the rate of 8% simple interest per annum. If he paid an amount of $5920 to clear the loan, then find the time period of the loan.

(2) Calculate the amount due if Thomas borrowed a sum of $3800 at 5% simple interest for 4 years.

(3) What amount will be due after 2 years if Charles borrowed a sum of $3450 at a 5% simple interest?

(4) In how much time a principal of $3000 will amount to $3180 at a simple interest of 2% per annum?

(5) Sarah took a loan of $5700 at the rate of 7% simple interest per annum. If he paid an amount of $8493 to clear the loan, then find the time period of the loan.

(6) Calculate the amount due after 10 years if Sarah borrowed a sum of $5850 at a rate of 3% simple interest.

(7) Calculate the amount due if Sarah borrowed a sum of $3850 at 7% simple interest for 3 years.

(8) If Barbara paid $3976 to settle his loan which he had taken 4 years before at a simple interest of 3%, then find the loan taken.

(9) Find the amount to be paid if Joseph borrowed a sum of $5700 at 10% simple interest for 8 years.

(10) If Karen paid $4582 to settle his loan which he had taken 4 years before at a simple interest of 4%, then find the loan taken.