Simple Interest
Math MCQs

Question :    Calculate the amount due after 10 years if Christopher borrowed a sum of $6000 at a rate of 10% simple interest.

Correct Answer  $12000

Solution & Explanation

Solution

Given,

Principal (P) = $6000

Rate of Simple Interest (SI) = 10%

Time (t) = 10 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% × 10

= $6000 ×¹⁰/₁₀₀ × 10

= ^{6000 × 10 × 10}/₁₀₀

= ^{60000 × 10}/₁₀₀

= ⁶⁰⁰⁰⁰⁰/₁₀₀

= $6000

Thus, Simple Interest = $6000

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 + $6000

= $12000

Thus, Amount to be paid = $12000 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) = 10 years

Thus, Amount (A)

= $6000 + ($6000 × 10% × 10)

= $6000 + ($6000 ×¹⁰/₁₀₀ × 10)

= $6000 + (^{6000 × 10 × 10}/₁₀₀)

= $6000 + (^{60000 × 10}/₁₀₀)

= $6000 + (⁶⁰⁰⁰⁰⁰/₁₀₀)

= $6000 + $6000 = $12000

Thus, Amount (A) to be paid = $12000 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 10 years

= Simple interest for 1 year × 10

= $600 × 10 = $6000

Thus, Simple Interest (SI) = $6000

Calculation of Amount

Amount = Principal + Interest

Thus, Amount = $6000 + $6000

= $12000

Thus, Amount to be paid = $12000 Answer

Similar Questions

(1) Calculate the amount due if Barbara borrowed a sum of $3550 at 10% simple interest for 4 years.

(2) What amount does Elizabeth have to pay after 5 years if he takes a loan of $3450 at 4% simple interest?

(3) Sarah took a loan of $5700 at the rate of 8% simple interest per annum. If he paid an amount of $9804 to clear the loan, then find the time period of the loan.

(4) How much loan did Margaret borrow 5 years ago at a rate of simple interest 3% per annum, if he paid $7302.5 to clear it?

(5) Kenneth had to pay $5600 in order to furnish the loan taken 3 years before. If the rate of simple interest was 4% then find the sum borrowed.

(6) How much loan did Jessica borrow 5 years ago at a rate of simple interest 2% per annum, if he paid $6325 to clear it?

(7) Find the amount to be paid if David borrowed a sum of $5400 at 6% simple interest for 8 years.

(8) What amount does William have to pay after 6 years if he takes a loan of $3500 at 5% simple interest?

(9) Margaret took a loan of $6700 at the rate of 10% simple interest per annum. If he paid an amount of $12730 to clear the loan, then find the time period of the loan.

(10) John took a loan of $4400 at the rate of 6% simple interest per annum. If he paid an amount of $5984 to clear the loan, then find the time period of the loan.