Simple Interest
Math MCQs

Question :    Calculate the amount due after 10 years if Robert borrowed a sum of $5100 at a rate of 2% simple interest.

Correct Answer  $6120

Solution & Explanation

Solution

Given,

Principal (P) = $5100

Rate of Simple Interest (SI) = 2%

Time (t) = 10 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% × 10

= $5100 ײ/₁₀₀ × 10

= ^{5100 × 2 × 10}/₁₀₀

= ^{10200 × 10}/₁₀₀

= ¹⁰²⁰⁰⁰/₁₀₀

= $1020

Thus, Simple Interest = $1020

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 + $1020

= $6120

Thus, Amount to be paid = $6120 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) = 10 years

Thus, Amount (A)

= $5100 + ($5100 × 2% × 10)

= $5100 + ($5100 ײ/₁₀₀ × 10)

= $5100 + (^{5100 × 2 × 10}/₁₀₀)

= $5100 + (^{10200 × 10}/₁₀₀)

= $5100 + (¹⁰²⁰⁰⁰/₁₀₀)

= $5100 + $1020 = $6120

Thus, Amount (A) to be paid = $6120 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 10 years

= Simple interest for 1 year × 10

= $102 × 10 = $1020

Thus, Simple Interest (SI) = $1020

Calculation of Amount

Amount = Principal + Interest

Thus, Amount = $5100 + $1020

= $6120

Thus, Amount to be paid = $6120 Answer

Similar Questions

(1) How much loan did William borrow 5 years ago at a rate of simple interest 5% per annum, if he paid $6875 to clear it?

(2) Linda had to pay $3651.5 in order to furnish the loan taken 3 years before. If the rate of simple interest was 3% then find the sum borrowed.

(3) How much loan did Sarah borrow 5 years ago at a rate of simple interest 4% per annum, if he paid $7020 to clear it?

(4) What amount will be due after 2 years if Joshua borrowed a sum of $3950 at a 5% simple interest?

(5) Richard took a loan of $5200 at the rate of 10% simple interest per annum. If he paid an amount of $9360 to clear the loan, then find the time period of the loan.

(6) Calculate the amount due after 10 years if Michael borrowed a sum of $5300 at a rate of 9% simple interest.

(7) Calculate the amount due if Barbara borrowed a sum of $3550 at 8% simple interest for 3 years.

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

(9) What amount will be due after 2 years if Daniel borrowed a sum of $3550 at a 10% simple interest?

(10) Sandra took a loan of $6900 at the rate of 7% simple interest per annum. If he paid an amount of $10764 to clear the loan, then find the time period of the loan.