Simple Interest
Math MCQs

Question :    Calculate the amount due if Susan borrowed a sum of $3650 at 10% simple interest for 3 years.

Correct Answer  $4745

Solution & Explanation

Solution

Given,

Principal (P) = $3650

Rate of Simple Interest (SI) = 10%

Time (t) = 3 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) = $3650 × 10% × 3

= $3650 ×¹⁰/₁₀₀ × 3

= ^{3650 × 10 × 3}/₁₀₀

= ^{36500 × 3}/₁₀₀

= ¹⁰⁹⁵⁰⁰/₁₀₀

= $1095

Thus, Simple Interest = $1095

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 = $3650 + $1095

= $4745

Thus, Amount to be paid = $4745 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 = $3650

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

And, Time (t) = 3 years

Thus, Amount (A)

= $3650 + ($3650 × 10% × 3)

= $3650 + ($3650 ×¹⁰/₁₀₀ × 3)

= $3650 + (^{3650 × 10 × 3}/₁₀₀)

= $3650 + (^{36500 × 3}/₁₀₀)

= $3650 + (¹⁰⁹⁵⁰⁰/₁₀₀)

= $3650 + $1095 = $4745

Thus, Amount (A) to be paid = $4745 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 $3650, the simple interest in 1 year

= ¹⁰/₁₀₀ × 3650

= ^{10 × 3650}/₁₀₀

= ³⁶⁵⁰⁰/₁₀₀ = $365

Thus, simple interest for 1 year = $365

Therefore, simple interest for 3 years

= Simple interest for 1 year × 3

= $365 × 3 = $1095

Thus, Simple Interest (SI) = $1095

Calculation of Amount

Amount = Principal + Interest

Thus, Amount = $3650 + $1095

= $4745

Thus, Amount to be paid = $4745 Answer

Similar Questions

(1) Calculate the amount due if Robert borrowed a sum of $3100 at 8% simple interest for 3 years.

(2) John took a loan of $4400 at the rate of 7% simple interest per annum. If he paid an amount of $6556 to clear the loan, then find the time period of the loan.

(3) Calculate the amount due if John borrowed a sum of $3200 at 5% simple interest for 3 years.

(4) What amount does James have to pay after 6 years if he takes a loan of $3000 at 8% simple interest?

(5) Find the amount to be paid if Elizabeth borrowed a sum of $5450 at 8% simple interest for 8 years.

(6) If Elizabeth paid $4140 to settle his loan which he had taken 4 years before at a simple interest of 5%, then find the loan taken.

(7) Find the amount to be paid if Robert borrowed a sum of $5100 at 4% simple interest for 7 years.

(8) Calculate the amount due if William borrowed a sum of $3500 at 4% simple interest for 3 years.

(9) How much loan did Richard borrow 5 years ago at a rate of simple interest 3% per annum, if he paid $6440 to clear it?

(10) Find the amount to be paid if Elizabeth borrowed a sum of $5450 at 5% simple interest for 7 years.