Simple Interest
Math MCQs

Question :    What amount will be due after 2 years if Matthew borrowed a sum of $3600 at a 10% simple interest?

Correct Answer  $4320

Solution & Explanation

Solution

Given,

Principal (P) = $3600

Rate of Simple Interest (SI) = 10%

Time (t) = 2 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) = $3600 × 10% × 2

= $3600 ×¹⁰/₁₀₀ × 2

= ^{3600 × 10 × 2}/₁₀₀

= ^{36000 × 2}/₁₀₀

= ⁷²⁰⁰⁰/₁₀₀

= $720

Thus, Simple Interest = $720

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 = $3600 + $720

= $4320

Thus, Amount to be paid = $4320 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 = $3600

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

And, Time (t) = 2 years

Thus, Amount (A)

= $3600 + ($3600 × 10% × 2)

= $3600 + ($3600 ×¹⁰/₁₀₀ × 2)

= $3600 + (^{3600 × 10 × 2}/₁₀₀)

= $3600 + (^{36000 × 2}/₁₀₀)

= $3600 + (⁷²⁰⁰⁰/₁₀₀)

= $3600 + $720 = $4320

Thus, Amount (A) to be paid = $4320 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 $3600, the simple interest in 1 year

= ¹⁰/₁₀₀ × 3600

= ^{10 × 3600}/₁₀₀

= ³⁶⁰⁰⁰/₁₀₀ = $360

Thus, simple interest for 1 year = $360

Therefore, simple interest for 2 years

= Simple interest for 1 year × 2

= $360 × 2 = $720

Thus, Simple Interest (SI) = $720

Calculation of Amount

Amount = Principal + Interest

Thus, Amount = $3600 + $720

= $4320

Thus, Amount to be paid = $4320 Answer

Similar Questions

(1) Betty had to pay $4505 in order to furnish the loan taken 3 years before. If the rate of simple interest was 2% then find the sum borrowed.

(2) Betty took a loan of $6500 at the rate of 6% simple interest per annum. If he paid an amount of $8840 to clear the loan, then find the time period of the loan.

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

(4) How much loan did George borrow 5 years ago at a rate of simple interest 4% per annum, if he paid $8760 to clear it?

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

(6) Sandra took a loan of $6900 at the rate of 10% simple interest per annum. If he paid an amount of $12420 to clear the loan, then find the time period of the loan.

(7) What amount will be due after 2 years if Richard borrowed a sum of $3300 at a 9% simple interest?

(8) Find the amount to be paid if Susan borrowed a sum of $5650 at 9% simple interest for 7 years.

(9) What amount does Mary have to pay after 6 years if he takes a loan of $3050 at 5% simple interest?

(10) Susan took a loan of $5300 at the rate of 6% simple interest per annum. If he paid an amount of $8162 to clear the loan, then find the time period of the loan.