Simple Interest
Math MCQs

Question :    Find the amount to be paid if Christopher borrowed a sum of $6000 at 10% simple interest for 8 years.

Correct Answer  $10800

Solution & Explanation

Solution

Given,

Principal (P) = $6000

Rate of Simple Interest (SI) = 10%

Time (t) = 8 years

Thus, Amount (A) = ?

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

Thus, here 10% simple interest means, Rate of Simple Interest (SI) is 10% 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) = $6000 × 10% × 8

= $6000 ×¹⁰/₁₀₀ × 8

= ^{6000 × 10 × 8}/₁₀₀

= ^{60000 × 8}/₁₀₀

= ⁴⁸⁰⁰⁰⁰/₁₀₀

= $4800

Thus, Simple Interest = $4800

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 = $6000 + $4800

= $10800

Thus, Amount to be paid = $10800 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 = $6000

Rate of Simple Interest (SI) or (R) = 10%

And, Time (t) = 8 years

Thus, Amount (A)

= $6000 + ($6000 × 10% × 8)

= $6000 + ($6000 ×¹⁰/₁₀₀ × 8)

= $6000 + (^{6000 × 10 × 8}/₁₀₀)

= $6000 + (^{60000 × 8}/₁₀₀)

= $6000 + (⁴⁸⁰⁰⁰⁰/₁₀₀)

= $6000 + $4800 = $10800

Thus, Amount (A) to be paid = $10800 Answer

Method (3) Unitary Method

Calculation of Amount using Unitary Method

Calculation of Interest using Unitary Method

Here, given Rate of Simple Interest = 10%

This, means, $10 per $100 per year

∵ For $100, the simple interest for 1 year = $10

∴ For $1, the simple interest for 1 year = ¹⁰/₁₀₀

∴ For $6000, the simple interest in 1 year

= ¹⁰/₁₀₀ × 6000

= ^{10 × 6000}/₁₀₀

= ⁶⁰⁰⁰⁰/₁₀₀ = $600

Thus, simple interest for 1 year = $600

Therefore, simple interest for 8 years

= Simple interest for 1 year × 8

= $600 × 8 = $4800

Thus, Simple Interest (SI) = $4800

Calculation of Amount

Amount = Principal + Interest

Thus, Amount = $6000 + $4800

= $10800

Thus, Amount to be paid = $10800 Answer

Similar Questions

(1) Lisa took a loan of $6100 at the rate of 6% simple interest per annum. If he paid an amount of $8296 to clear the loan, then find the time period of the loan.

(2) Find the amount to be paid if Christopher borrowed a sum of $6000 at 3% simple interest for 7 years.

(3) In how much time a principal of $3100 will amount to $3596 at a simple interest of 4% per annum?

(4) Calculate the amount due after 10 years if Christopher borrowed a sum of $6000 at a rate of 6% simple interest.

(5) Calculate the amount due after 9 years if Charles borrowed a sum of $5900 at a rate of 7% simple interest.

(6) Thomas had to pay $4142 in order to furnish the loan taken 3 years before. If the rate of simple interest was 3% then find the sum borrowed.

(7) James took a loan of $4000 at the rate of 8% simple interest per annum. If he paid an amount of $6240 to clear the loan, then find the time period of the loan.

(8) Find the amount to be paid if James borrowed a sum of $5000 at 8% simple interest for 7 years.

(9) Calculate the amount due after 10 years if David borrowed a sum of $5400 at a rate of 7% simple interest.

(10) Calculate the amount due if Robert borrowed a sum of $3100 at 9% simple interest for 4 years.