Simple Interest
Math MCQs

Question :  ( 1 of 10 )  Find the amount to be paid if Robert borrowed a sum of $5100 at 6% simple interest for 8 years.

Correct Answer  $7548

Solution & Explanation

Solution

Given,

Principal (P) = $5100

Rate of Simple Interest (SI) = 6%

Time (t) = 8 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) = $5100 × 6% × 8

= $5100 ×⁶/₁₀₀ × 8

= ^{5100 × 6 × 8}/₁₀₀

= ^{30600 × 8}/₁₀₀

= ²⁴⁴⁸⁰⁰/₁₀₀

= $2448

Thus, Simple Interest = $2448

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 + $2448

= $7548

Thus, Amount to be paid = $7548 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) = 6%

And, Time (t) = 8 years

Thus, Amount (A)

= $5100 + ($5100 × 6% × 8)

= $5100 + ($5100 ×⁶/₁₀₀ × 8)

= $5100 + (^{5100 × 6 × 8}/₁₀₀)

= $5100 + (^{30600 × 8}/₁₀₀)

= $5100 + (²⁴⁴⁸⁰⁰/₁₀₀)

= $5100 + $2448 = $7548

Thus, Amount (A) to be paid = $7548 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 $5100, the simple interest in 1 year

= ⁶/₁₀₀ × 5100

= ^{6 × 5100}/₁₀₀

= ³⁰⁶⁰⁰/₁₀₀ = $306

Thus, simple interest for 1 year = $306

Therefore, simple interest for 8 years

= Simple interest for 1 year × 8

= $306 × 8 = $2448

Thus, Simple Interest (SI) = $2448

Calculation of Amount

Amount = Principal + Interest

Thus, Amount = $5100 + $2448

= $7548

Thus, Amount to be paid = $7548 Answer

Similar Questions

(1) Elizabeth took a loan of $4900 at the rate of 8% simple interest per annum. If he paid an amount of $8036 to clear the loan, then find the time period of the loan.

(2) What amount does Thomas have to pay after 6 years if he takes a loan of $3800 at 7% simple interest?

(3) Joseph took a loan of $5400 at the rate of 10% simple interest per annum. If he paid an amount of $10800 to clear the loan, then find the time period of the loan.

(4) Calculate the amount due after 10 years if Barbara borrowed a sum of $5550 at a rate of 3% simple interest.

(5) If Kimberly paid $5580 to settle his loan which he had taken 4 years before at a simple interest of 5%, then find the loan taken.

(6) Calculate the amount due if Joseph borrowed a sum of $3700 at 7% simple interest for 3 years.

(7) What amount does Christopher have to pay after 5 years if he takes a loan of $4000 at 8% simple interest?

(8) Karen took a loan of $5900 at the rate of 8% simple interest per annum. If he paid an amount of $10620 to clear the loan, then find the time period of the loan.

(9) How much loan did Jessica borrow 5 years ago at a rate of simple interest 3% per annum, if he paid $6612.5 to clear it?

(10) Find the amount to be paid if Barbara borrowed a sum of $5550 at 3% simple interest for 7 years.