Simple Interest
Math MCQs

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

Correct Answer  $8364

Solution & Explanation

Solution

Given,

Principal (P) = $5100

Rate of Simple Interest (SI) = 8%

Time (t) = 8 years

Thus, Amount (A) = ?

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

Thus, here 8% simple interest means, Rate of Simple Interest (SI) is 8% 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 × 8% × 8

= $5100 ×⁸/₁₀₀ × 8

= ^{5100 × 8 × 8}/₁₀₀

= ^{40800 × 8}/₁₀₀

= ³²⁶⁴⁰⁰/₁₀₀

= $3264

Thus, Simple Interest = $3264

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 + $3264

= $8364

Thus, Amount to be paid = $8364 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) = 8%

And, Time (t) = 8 years

Thus, Amount (A)

= $5100 + ($5100 × 8% × 8)

= $5100 + ($5100 ×⁸/₁₀₀ × 8)

= $5100 + (^{5100 × 8 × 8}/₁₀₀)

= $5100 + (^{40800 × 8}/₁₀₀)

= $5100 + (³²⁶⁴⁰⁰/₁₀₀)

= $5100 + $3264 = $8364

Thus, Amount (A) to be paid = $8364 Answer

Method (3) Unitary Method

Calculation of Amount using Unitary Method

Calculation of Interest using Unitary Method

Here, given Rate of Simple Interest = 8%

This, means, $8 per $100 per year

∵ For $100, the simple interest for 1 year = $8

∴ For $1, the simple interest for 1 year = ⁸/₁₀₀

∴ For $5100, the simple interest in 1 year

= ⁸/₁₀₀ × 5100

= ^{8 × 5100}/₁₀₀

= ⁴⁰⁸⁰⁰/₁₀₀ = $408

Thus, simple interest for 1 year = $408

Therefore, simple interest for 8 years

= Simple interest for 1 year × 8

= $408 × 8 = $3264

Thus, Simple Interest (SI) = $3264

Calculation of Amount

Amount = Principal + Interest

Thus, Amount = $5100 + $3264

= $8364

Thus, Amount to be paid = $8364 Answer

Similar Questions

(1) Anthony took a loan of $6600 at the rate of 7% simple interest per annum. If he paid an amount of $9834 to clear the loan, then find the time period of the loan.

(2) Calculate the amount due after 10 years if Linda borrowed a sum of $5350 at a rate of 10% simple interest.

(3) What amount does Jennifer have to pay after 6 years if he takes a loan of $3250 at 2% simple interest?

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

(5) Patricia took a loan of $4300 at the rate of 6% simple interest per annum. If he paid an amount of $5848 to clear the loan, then find the time period of the loan.

(6) Calculate the amount due if Michael borrowed a sum of $3300 at 3% simple interest for 3 years.

(7) Michael took a loan of $4600 at the rate of 8% simple interest per annum. If he paid an amount of $7176 to clear the loan, then find the time period of the loan.

(8) Calculate the amount due if Joseph borrowed a sum of $3700 at 3% simple interest for 3 years.

(9) Nancy took a loan of $6300 at the rate of 6% simple interest per annum. If he paid an amount of $8946 to clear the loan, then find the time period of the loan.

(10) Calculate the amount due after 9 years if Jessica borrowed a sum of $5750 at a rate of 8% simple interest.